Shareholders' Equity (Details) - USD ($) $ in Millions	12 Months Ended	32 Months Ended
	Dec. 31, 2016	Mar. 31, 2017	May 25, 2016
Shareholders' Equity [Abstract]
Stock Repurchase Program Authorized Percent Of Common Stock			5.00%
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			921,000
Treasury Stock, Shares, Acquired	1,398,026	2,519,584
Treasury Stock, Amount, Acquired	$ 22.1	$ 40.8