Common Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Apr. 20, 2021
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Number of shares repurchased (in shares)	2,600,000	5,000,000.0
Cost of shares repurchased	$ 400,000	$ 756,000
Average cost per share repurchased (in dollars per share)	$ 157.18	$ 152.65
Number of shares acquired to cover tax withholding costs and exercise costs (in shares)	917	300,000
Cost of shares acquired to cover tax withholding costs and exercise costs	$ 144	$ 42,000
Additional share repurchase authorization			$ 5,000,000
Remaining capacity under share repurchase authorization	$ 5,410,000	$ 5,410,000