Share Repurchase Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 16, 2019	Mar. 19, 2018
Equity, Class of Treasury Stock [Line Items]
Repurchased common shares (in shares)	411,430	470,708	321,731
Cost to repurchase common shares	$ 12,559,000	$ 18,222,000	$ 12,256,000
March 19, 2018 Plan
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 50,000,000
Repurchased common shares (in shares)	792,439	470,708	321,731
Cost to repurchase common shares	$ 30,500,000	$ 18,200,000	$ 12,300,000
Cost to repurchase common shares (in dollars per share)	$ 38.46	$ 38.71	$ 38.10
September 16, 2019 Plan
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount				$ 50,000,000
Repurchased common shares (in shares)	411,430	0
Cost to repurchase common shares	$ 12,600,000
Cost to repurchase common shares (in dollars per share)	$ 30.52