Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under the 2016 Plan (in shares)	4,602,225		4,602,225
Stock options, granted (in shares)			443,936
Stock options, weighted average exercise price (in dollars per share)			$ 83.88
Stock options, weighted average grant date fair value (in dollars per share)			$ 18.04
Risk-free interest rate (in hundredths)			2.04%
Expected life (in years)			5 years 11 months
Stock volatility (in hundredths)			19.90%
Dividend yield (in hundredths)			0.70%
Stock-based compensation expense	$ 4.6	$ 4.6	$ 13.6	$ 14.1
Performance Share Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			91,803
Grant date fair value (in dollars per share)			$ 83.97
Number of shares of common stock per PSU award (in shares)	1		1
Performance period			3 years
PSU payout, Minimum (in hundredths)	0.00%		0.00%
PSU payout, Maximum (in hundredths)	200.00%		200.00%