Quarterly report pursuant to Section 13 or 15(d)

Business Segment Information (Details)

v3.10.0.1
Business Segment Information (Details) - USD ($)
 3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Segment Reporting Information [Line Items]        
Revenues $ 205,375,000 $ 204,744,000 $ 569,767,000 $ 506,019,000
Interest income 76,000 41,000 209,000 87,000
Interest expense 3,776,000 2,791,000 10,721,000 7,555,000
Depreciation and amortization of intangible assets 7,214,000 6,186,000 21,001,000 17,592,000
Unallocated corporate activity 0   0  
Income before taxes, excluding unallocated corporate activity 22,699,000 19,511,000 52,054,000 38,234,000
U.S. Regions        
Segment Reporting Information [Line Items]        
Revenues 86,402,000   249,871,000  
U.S. Federal        
Segment Reporting Information [Line Items]        
Revenues 62,378,000   168,377,000  
Canada        
Segment Reporting Information [Line Items]        
Revenues 11,604,000   28,466,000  
Non-Solar DG        
Segment Reporting Information [Line Items]        
Revenues 22,138,000   60,176,000  
All Other        
Segment Reporting Information [Line Items]        
Revenues 22,853,000   62,877,000  
Operating Segments | U.S. Regions        
Segment Reporting Information [Line Items]        
Revenues 86,402,000 82,633,000 249,871,000 191,956,000
Interest income 2,000 1,000 5,000 2,000
Interest expense 1,403,000 856,000 3,911,000 1,950,000
Depreciation and amortization of intangible assets 1,341,000 867,000 4,048,000 1,940,000
Income before taxes, excluding unallocated corporate activity 5,256,000 6,432,000 14,606,000 7,388,000
Operating Segments | U.S. Federal        
Segment Reporting Information [Line Items]        
Revenues 62,378,000 63,873,000 168,377,000 170,903,000
Interest income 36,000 14,000 84,000 29,000
Interest expense 225,000 292,000 771,000 888,000
Depreciation and amortization of intangible assets 671,000 644,000 2,004,000 1,951,000
Income before taxes, excluding unallocated corporate activity 10,969,000 8,753,000 26,864,000 23,079,000
Operating Segments | Canada        
Segment Reporting Information [Line Items]        
Revenues 11,604,000 14,719,000 28,466,000 33,211,000
Interest income 0 0 0 1,000
Interest expense 480,000 512,000 1,464,000 1,465,000
Depreciation and amortization of intangible assets 294,000 303,000 873,000 878,000
Income before taxes, excluding unallocated corporate activity 664,000 1,537,000 (1,983,000) 1,638,000
Operating Segments | Non-Solar DG        
Segment Reporting Information [Line Items]        
Revenues 22,138,000 22,847,000 60,176,000 53,703,000
Interest income 38,000 26,000 120,000 55,000
Interest expense 1,681,000 1,118,000 4,575,000 3,214,000
Depreciation and amortization of intangible assets 4,530,000 3,875,000 12,942,000 11,416,000
Income before taxes, excluding unallocated corporate activity 3,851,000 1,798,000 8,796,000 3,825,000
Operating Segments | All Other        
Segment Reporting Information [Line Items]        
Revenues 22,853,000 20,672,000 62,877,000 56,246,000
Interest income 0 0 0 0
Interest expense (13,000) 13,000 0 38,000
Depreciation and amortization of intangible assets 378,000 497,000 1,134,000 1,407,000
Income before taxes, excluding unallocated corporate activity 1,959,000 991,000 3,771,000 2,304,000
Unallocated corporate activity        
Segment Reporting Information [Line Items]        
Unallocated corporate activity $ (8,648,000) $ (6,839,000) $ (23,268,000) $ (20,931,000)