Equity Transactions - Additional Information (Details) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Aug. 19, 2020 $ / shares	Feb. 03, 2020 day $ / shares shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares	May 31, 2020 shares
Equity, Class of Treasury Stock [Line Items]
Preferred stock conversion, threshold consecutive trading days | day		20
Cash dividends declared per common share (in $ per share) | $ / shares	$ 0.82		$ 0.82	$ 0.67	$ 2.16	$ 1.77
Number of additional shares authorized to be repurchased (in shares)							750,000
Total number of shares authorized to be repurchased since inception (in shares)							4,930,045
Repurchases of common shares (in shares)			53,867		239,720
Weighted average price (in $ per share) | $ / shares			$ 139.20		$ 104.26
Total cost of shares repurchased | $			$ 7,500	$ 7,501	$ 25,000	$ 30,000
Shares available for repurchase (in shares)			762,718		762,718
Convertible preferred stock
Equity, Class of Treasury Stock [Line Items]
Preferred stock, shares issuable upon conversion (in shares)		1,150,000
Conversion ratio		0.7938
Conversion price of stock (in $ per share) | $ / shares		$ 125.97
Common stock
Equity, Class of Treasury Stock [Line Items]
Shares issued during period, conversion of convertible preferred stock (in shares)		912,870