Stockholders' Equity Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity Attributable to Parent [Abstract]
Stock Repurchased and Retired During Period, Value	$ 70,000	$ 154,516	$ 306,393
Stock Repurchased and Retired During Period, Shares	1,953,711	3,987,945	5,849,234
Stock Repurchase and Retired During Period, Weighted Average Price	$ 35.83	$ 38.75	$ 52.38
Treasury Shares Surrendered	$ 5,369	$ 8,449	$ 9,149