Shareholders' Equity Common Stock Repurchase Plans (Details) - USD ($)	1 Months Ended				12 Months Ended
	Oct. 31, 2019	Mar. 31, 2019	Nov. 30, 2018	Nov. 30, 2017	Dec. 31, 2019	Dec. 31, 2018
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase amount					$ 111,457,000	$ 95,308,000
Common Stock | October 2019 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Treasury stock, value	$ 100,000,000.0
Acquisition of treasury stock (in shares)	0
Percent of common shares outstanding, expected to be delivered	3.90%
Common Stock | March 2019 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Treasury stock, value		$ 100,000,000.0
Common stock repurchase amount					$ 100,000,000.0
Average cost per share of treasury stock acquired (usd per share)					$ 16.28
Acquisition of treasury stock (in shares)					6,100,000
Percent of common shares outstanding, expected to be delivered		3.50%
Common Stock | November 2017 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Treasury stock, value				$ 50,000,000.0
Common stock repurchase amount						$ 31,500,000
Average cost per share of treasury stock acquired (usd per share)						$ 16.71
Acquisition of treasury stock (in shares)						1,900,000
Percent of common shares outstanding, expected to be delivered				2.30%
Common Stock | November 2018 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Treasury stock, value			$ 75,000,000.0
Common stock repurchase amount					$ 75,000,000.0
Average cost per share of treasury stock acquired (usd per share)					$ 15.57
Acquisition of treasury stock (in shares)					706,000	4,100,000
Percent of common shares outstanding, expected to be delivered			2.70%