Shareholders' Equity (Details) - USD ($) $ in Millions	12 Months Ended		29 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	May 25, 2016
Treasury Stock, Shares, Acquired	1,398,026		2,519,584
Treasury Stock, Amount, Acquired	$ 22.1		$ 40.8
Employee Stock Purchase Plan [Member]
Common stock reserved for issuance	150,000		150,000
Common stock issued, shares	61,115	59,873
Treasury shares reissued	52,500	52,500
2008 Stock Based Award Plan [Member]
Common stock reserved for issuance	800,000		800,000
Common stock issued, shares	603,545	512,101
Treasury shares reissued	25,725	25,725
2016 Stock Repurchase Program [Member]
Stock Repurchase Program Authorized Percent Of Common Stock				5.00%
Stock Repurchase Program, Number of Shares Authorized to be Repurchased				921,000