Earnings per Share Repurchase of Common Stock (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2015
Stock Repurchased and Retired During Period, Value		$ 31,570	$ 14,750	$ 670
10b5-1 share repurchase program [Member]
Stock Repurchase Program, Authorized Amount	$ 250,000				$ 250,000		$ 50,000
Stock Repurchased and Retired During Period, Shares	0		502,500		1,253,650	527,400
Stock Repurchased and Retired During Period, Value			$ 14,700		$ 31,600	$ 15,400