Stockholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	May 24, 2018
Equity, Class of Treasury Stock [Line Items]
Treasury stock shares	800,000	900,000
Treasury stock, Cost basis	$ 14.2	$ 18.5
2018 Stock Buyback Program [Member]
Equity, Class of Treasury Stock [Line Items]
Shares authorized for repurchase			5.00%
Number of shares authorized for repurchase			4,300,000
Shares repurchased	200,000
Shares purchased price per share	$ 41.30
Restricted Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares nonvested	1,300,000	1,300,000