Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Selected Quarterly Financial Data (Unaudited)
Revenue	$ 719,584	$ 706,918	$ 650,302	$ 538,473	$ 588,359	$ 594,536	$ 535,043	$ 464,941	$ 2,615,277	$ 2,182,879	$ 1,787,922
Gross Profit	132,560	142,702	120,016	106,665	118,175	127,868	111,183	89,053	501,943	446,279	366,281
Net income	$ 34,052	$ 36,233	$ 24,173	$ 19,866	$ 25,156	$ 38,541	$ 32,547	$ 16,659	$ 114,324	$ 112,903	$ 55,272
Basic-
Basic (in dollars per share)	$ 0.93	$ 0.98	$ 0.65	$ 0.54	$ 0.68	$ 1.03	$ 0.87	$ 0.45	$ 3.10	$ 3.03	$ 1.48
Diluted-
Diluted (in dollars per share)	$ 0.92	$ 0.98	$ 0.65	$ 0.53	$ 0.67	$ 1.02	$ 0.87	$ 0.44	$ 3.08	$ 3.00	$ 1.47
Gain due to insurance proceeds received	$ 4,800