Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effect of Fourth Quarter Events [Line Items]
Total revenues	$ 4,186,841	$ 3,999,374	$ 3,907,270	$ 3,700,856	$ 3,285,755	$ 2,984,859	$ 2,785,464	$ 2,636,635	$ 2,477,541	$ 2,290,188	$ 2,105,204	$ 1,957,736	$ 15,794,341	$ 11,692,713	$ 8,830,669
Gross profit	1,453,441	1,468,246	1,504,839	1,400,277	1,071,421	898,620	793,768	895,904
Net income	$ 133,934	$ 402,835	$ 384,349	$ 290,124	$ 185,517	$ 129,590	$ 65,600	$ 178,222					$ 1,211,242	$ 558,929	$ 186,678
Earnings (loss) per share:
Basic (in USD per share)	$ 0.31	$ 0.92	$ 0.88	$ 0.67	$ 0.43	$ 0.30	$ 0.15	$ 0.41					$ 2.78	$ 1.29	$ 0.44
Diluted (in USD per share)	$ 0.30	$ 0.89	$ 0.85	$ 0.64	$ 0.41	$ 0.29	$ 0.15	$ 0.40					$ 2.68	$ 1.25	$ 0.43
As Previously Reported
Effect of Fourth Quarter Events [Line Items]
Total revenues		$ 3,999,374	$ 3,907,270	$ 3,700,856	$ 3,285,755	$ 2,984,859	$ 2,785,464	$ 2,636,635	$ 2,477,541	$ 2,290,188	$ 2,105,204	$ 1,957,736		$ 11,692,713	$ 8,830,669