Unaudited Quarterly Financial Results (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information
Revenues	$ 401,659,000	$ 388,283,000	$ 282,685,000	$ 167,078,000	$ 161,790,000	$ 162,370,000	$ 143,683,000	$ 129,438,000	$ 1,239,705,000	$ 597,281,000	$ 438,065,000
Gross Profit	121,282,000	119,039,000	88,954,000	55,048,000	53,629,000	54,528,000	48,794,000	43,154,000	384,323,000	200,105,000	149,456,000
Net income (loss)	11,322,000	17,433,000	8,515,000	5,383,000	7,501,000	7,767,000	5,865,000	3,164,000	42,653,000	24,297,000	(9,897,000)
Earnings per share:
Basic (in dollars per share)	$ 0.22	$ 0.33	$ 0.19	$ 0.14	$ 0.20	$ 0.21	$ 0.16	$ 0.09	$ 0.91	$ 0.66	$ (0.27)
Diluted (in dollars per share)	$ 0.21	$ 0.33	$ 0.19	$ 0.14	$ 0.20	$ 0.21	$ 0.16	$ 0.08	$ 0.89	$ 0.64	$ (0.27)
Vendor Fees [Member] | Apex Systems
Segment Reporting Information
Classification error related to vendor fees		$ 500,000