Annual report pursuant to Section 13 and 15(d)

Goodwill and Intangible Assets - Narrative (Details)

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Goodwill and Intangible Assets - Narrative (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Goodwill [Line Items]      
Percent of Goodwill Fair Value that Exceeds Carrying Val 13.00% 13.00%  
Goodwill $ 57,976 $ 59,085 $ 60,479
U.S. Regions      
Goodwill [Line Items]      
Goodwill 24,759 24,759 24,759
Other      
Goodwill [Line Items]      
Goodwill $ 26,580 $ 27,789 $ 28,564
Integrated-PV      
Goodwill [Line Items]      
Percent of Goodwill Fair Value that Exceeds Carrying Val   5.00%  
Goodwill   $ 7,600  
Southwest Reporting Unit | U.S. Regions      
Goodwill [Line Items]      
Percent of Goodwill Fair Value that Exceeds Carrying Val 9.00%    
Goodwill $ 16,829