Segment Reporting - Summary of Revenues, Gross Profit and Operating Income (Loss) by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 337,096	$ 322,868	$ 646,262	$ 629,102
Gross profit	72,053	71,918	131,243	132,981
Operating income (loss)	14,523	20,619	23,648	29,753
Reportable Geographical Components [Member] | United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	252,834	227,618	475,975	438,248
Gross profit	54,639	50,891	92,493	92,284
Operating income (loss)	10,644	11,693	7,724	14,089
Reportable Geographical Components [Member] | Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	39,400	42,212	86,052	84,075
Gross profit	8,491	9,934	20,680	18,996
Operating income (loss)	4,836	6,129	13,442	11,552
Reportable Geographical Components [Member] | Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	13,646	21,175	27,763	43,791
Gross profit	3,835	4,543	8,060	9,301
Operating income (loss)	469	851	1,940	1,378
Reportable Geographical Components [Member] | Other Foreign [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	31,216	31,863	56,472	62,988
Gross profit	5,088	6,550	10,010	12,400
Operating income (loss)	$ (1,426)	$ 1,946	$ 542	$ 2,734