Shareholders' Equity - Treasury Stock (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended		8 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Nov. 14, 2016	May 02, 2012
Equity [Abstract]
Number of shares authorized to be repurchased (in shares)					500,000.0	500,000
Number shares repurchased (in shares)	0	0		24,086
Payments for repurchase of common stock		$ 0.0	$ 0.2	$ 0.2
Remaining number of shares authorized to be repurchased (in shares)	475,914	475,914		475,914
Average price per share of treasury stock acquired and held (in dollars per share)		$ 39.19
Movement in Treasury Stock [Roll Forward]
Beginning balance (in shares)		744,091
Restricted stock grants (in shares)		(86,000)
Forfeitures and other (in shares)		67,767
Ending balance (in shares)	725,858	725,858		725,858