Stock Based Compensation (Restricted Stock Units Activity) (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, Outstanding at Beginning of Year	408,507
Shares, Granted	285,258
Shares, Vested	(362,098)
Shares, Canceled	(9,471)
Shares, Outstanding at End of Year	322,196	408,507
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares, Outstanding at Beginning of Year, Weighted Average Grant Date Fair Value	$ 34.95
Shares, Granted, Weighted Average Grant Date Fair Value	42.28	$ 39.65	$ 35.16
Shares, Vested, Weighted Average Grant Date Fair Value	37.23
Shares, Canceled, Weighted Average Grant Date Fair Value	39.67
Shares, Outstanding at End of Year, Weighted Average Grant Date Fair Value	$ 38.75	$ 34.95
Shares, Outstanding at End of Year, Weighted Average Remaining Years Contractual Term	1 year
Shares, Outstanding at End of Year, Aggregate Intrinsic Value	$ 14,137,960