Repurchases of Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Equity [Abstract]
Shares repurchased in the open market (in shares)	274	0	892	721
Shares acquired through employee surrender for statutory tax withholding (in shares)	1	1	29	31
Total shares repurchased (in shares)	275	1	921	752
Cost of shares repurchased in the open market	$ 183,315	$ 0	$ 510,937	$ 179,623
Cost of shares for employee surrenders	515	360	15,501	9,029
Total cost of shares	$ 183,830	$ 360	$ 526,438	$ 188,652
Average cost per share - open market repurchases (in USD per share)	$ 668.33	$ 0	$ 572.10	$ 249.20
Average cost per share - employee surrenders (in USD per share)	688.35	393.12	547.90	292.03
Average cost per share - total (in USD per share)	$ 668.38	$ 393.12	$ 571.36	$ 250.96