Stock Based Compensation (Restricted Stock Units Activity) (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	1,069,029
Shares, Granted	318,805
Shares, Vested	(963,387)
Shares, Canceled	(15,940)
Shares, Outstanding at End of Year	408,507	1,069,029
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	$ 32.49
Shares, Granted, Weighted Average Grant Date Fair Value	39.65	$ 35.16	$ 31.41
Shares, Vested, Weighted Average Grant Date Fair Value	33.73
Shares, Canceled, Weighted Average Grant Date Fair Value	37.28
Shares, Outstanding at End of Year, Weighted Average Grant Date Fair Value	$ 34.95	$ 32.49
Shares, Outstanding at End of Year, Weighted Average Remaining Years Contractual Term	1 year 1 month 5 days
Shares, Outstanding at End of Year, Aggregate Intrinsic Value	$ 15,805,175