Equity Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Aug. 18, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Equity [Abstract]
Cash dividends declared per common share (in $ per share)	$ 1.50	$ 1.50	$ 0.82	$ 3.14	$ 2.16
Repurchases of common shares (in shares)		64,494		111,327
Weighted average price (in $ per share)		$ 310.07		$ 291.90
Total cost of shares repurchased		$ 20,000	$ 7,500	$ 32,499	$ 25,000
Shares available for repurchase (in shares)		611,315		611,315