Stockholders' Equity (Details) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) shares	Sep. 30, 2019 USD ($) vote $ / shares shares	Sep. 30, 2018 USD ($) shares
Accumulated Other Comprehensive Income (Loss) [Line Items]
Common stock shares authorized (in shares) | shares	300,000,000.0		300,000,000.0
Common stock par value (USD per share) | $ / shares	$ 0.01		$ 0.01
Preferred stock authorized shares (in shares) | shares	10,000,000.0		10,000,000.0
Preferred stock par or stated value (in dollars per share) | $ / shares	$ 0.01		$ 0.01
Common stock, number of votes granted per common share held | vote			1
Treasury stock, acquired (in shares) | shares	700,000	0	700,000	0
Payments for repurchase of common stock	$ 50.0		$ 52.3
Value of treasury stock acquired	50.0	$ 0.5	55.5	$ 3.5
February 2016 Program
Accumulated Other Comprehensive Income (Loss) [Line Items]
Remaining shares under share repurchase authorization	174.6		174.6
NEW YORK STOCK EXCHANGE, INC.
Accumulated Other Comprehensive Income (Loss) [Line Items]
Value of treasury stock acquired	$ 0.0	$ 0.5	$ 3.2	$ 3.5