Shareholders' Equity Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock Repurchased and Retired During Period, Shares	82,016			82,616
Stock Repurchased and Retired During Period, Value	$ 7.1			$ 7.1
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 192.8			$ 192.8
Dividends [Abstract]
Dividends declared per share	$ 0.10	$ 0.10	$ 0.00	$ 0.20	$ 0.00
2016 Share Repurchase Program [Member]
Stock Repurchase Program, Authorized Amount	$ 250.0			$ 250.0
2014 Share Repurchase Program [Member]
Stock Repurchase Program, Authorized Amount	$ 200.0			$ 200.0