Annual report pursuant to Section 13 and 15(d)

Business Segment Information - Segment Information (Details)

v3.6.0.2
Business Segment Information - Segment Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Segment Reporting Information [Line Items]                      
Revenues $ 174,225 $ 180,598 $ 162,628 $ 133,776 $ 173,768 $ 189,142 $ 152,489 $ 115,433 $ 651,227 $ 630,832 $ 593,241
Interest income                 49 1,329 45
Interest income                 7,088 5,250 4,557
Depreciation and intangible asset amortization                 22,800 21,522 20,909
Unallocated corporate activity                 32,181 25,671 27,621
Income (loss) before taxes, excluding unallocated corporate activity                 48,548 25,963 33,913
Operating Segments | U.S. Regions                      
Segment Reporting Information [Line Items]                      
Revenues                 269,766 301,371 263,451
Interest income                 0 0 0
Interest income                 0 0 0
Depreciation and intangible asset amortization                 490 838 1,352
Income (loss) before taxes, excluding unallocated corporate activity                 18,200 24,800 24,849
Operating Segments | U.S. Federal                      
Segment Reporting Information [Line Items]                      
Revenues                 177,991 127,620 106,192
Interest income                 11 0 0
Interest income                 942 0 0
Depreciation and intangible asset amortization                 2,588 1,209 1,178
Income (loss) before taxes, excluding unallocated corporate activity                 22,236 16,676 14,035
Operating Segments | Canada                      
Segment Reporting Information [Line Items]                      
Revenues                 50,448 49,235 70,492
Interest income                 0 1,154 1
Interest income                 1,737 1,338 1,369
Depreciation and intangible asset amortization                 1,090 1,081 1,288
Income (loss) before taxes, excluding unallocated corporate activity                 (2,330) (15,449) (7,838)
Operating Segments | Small-Scale Infrastructure                      
Segment Reporting Information [Line Items]                      
Revenues                 81,395 66,322 58,286
Interest income                 38 175 43
Interest income                 4,386 3,912 3,188
Depreciation and intangible asset amortization                 16,004 14,316 12,892
Income (loss) before taxes, excluding unallocated corporate activity                 10,859 8,613 3,191
Operating Segments | Other                      
Segment Reporting Information [Line Items]                      
Revenues                 71,627 86,284 94,820
Interest income                 0 0 1
Interest income                 23 0 0
Depreciation and intangible asset amortization                 2,628 4,078 4,199
Income (loss) before taxes, excluding unallocated corporate activity                 (417) (8,677) (324)
Consolidation, Eliminations                      
Segment Reporting Information [Line Items]                      
Unallocated corporate activity                 (32,181) (25,671) (27,621)
Consolidation, Eliminations | U.S. Regions                      
Segment Reporting Information [Line Items]                      
Unallocated corporate activity                 0 0 0
Consolidation, Eliminations | U.S. Federal                      
Segment Reporting Information [Line Items]                      
Unallocated corporate activity                 0 0 0
Consolidation, Eliminations | Canada                      
Segment Reporting Information [Line Items]                      
Unallocated corporate activity                 0 0 0
Consolidation, Eliminations | Small-Scale Infrastructure                      
Segment Reporting Information [Line Items]                      
Unallocated corporate activity                 0 0 0
Consolidation, Eliminations | Other                      
Segment Reporting Information [Line Items]                      
Unallocated corporate activity                 $ 0 $ 0 $ 0