Shareholders' Equity - Dividends and Stock Repurchase Programs (Details) - USD ($) $ / shares in Units, shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 31, 2019	Oct. 31, 2017
Equity [Abstract]
Cash dividends declared	$ 23,600,000	$ 16,100,000	$ 16,300,000
Cash dividends declared (in dollars per share)	$ 0.36	$ 0.24	$ 0.24
Authorized amount					$ 100,000,000
Increase to repurchase program				$ 100,000,000
Amount available to repurchase shares under stock repurchase program	$ 114,600,000			$ 150,000,000
Shares repurchased (in shares)	2.1	0.7	1.7
Amount of shares repurchased (in shares)	$ 65,400,000	$ 20,000,000.0	$ 61,900,000