Stock Repurchases (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 06, 2017
Stock Repurchases [Abstract]
Stock Repurchase Program, Authorized Repurchase Amount				$ 150,000,000.0
Stock Repurchased During Period, Shares	996,773	687,048	1,479,454
Stock Repurchased During Period, Value	$ 49,600,000	$ 39,400,000	$ 65,300,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 84,200,000