Earnings per Share Repurchase of Common Stock (Details) - USD ($)	3 Months Ended					9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2015
Stock Repurchased and Retired During Period, Value	$ 3,950,000	$ 11,570,000	$ 2,640,000	$ 4,480,000	$ 31,570,000
10b5-1 share repurchase program [Member]
Stock Repurchase Program, Authorized Amount	$ 250,000,000					$ 250,000,000		$ 50,000,000
Stock Repurchased and Retired During Period, Shares	129,866			188,028		570,084	1,441,678
Stock Repurchased and Retired During Period, Value	$ 4,000,000			$ 4,500,000		$ 18,200,000	$ 36,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 143,500,000					$ 143,500,000