Equity Compensation (Stock Options Outstanding by Exercise Price) (Details) - $ / shares	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 21.13	$ 21.22
$ 13.37 – $20.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	13.37
Exercise price range, upper limit (in dollars per share)	20.00
$ 20.01 – $25.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	20.01
Exercise price range, upper limit (in dollars per share)	25.00
$ 25.01 – $30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	25.01
Exercise price range, upper limit (in dollars per share)	30.00
$ 30.01 – $33.36
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	30.01
Exercise price range, upper limit (in dollars per share)	$ 33.36
Stock Options
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Number Outstanding at end of period (in shares)	2,606,820
Options Outstanding - Weighted Average Remaining Contractual Life	3 years 8 months
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 21.13
Options Exercisable - Number Exercisable At end of period (in shares)	2,530,477
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 21.33
Stock Options | $ 13.37 – $20.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Number Outstanding at end of period (in shares)	720,008
Options Outstanding - Weighted Average Remaining Contractual Life	5 years 8 months
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 14.12
Options Exercisable - Number Exercisable At end of period (in shares)	643,665
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 14.06
Stock Options | $ 20.01 – $25.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Number Outstanding at end of period (in shares)	1,118,478
Options Outstanding - Weighted Average Remaining Contractual Life	3 years
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 22.58
Options Exercisable - Number Exercisable At end of period (in shares)	1,118,478
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 22.58
Stock Options | $ 25.01 – $30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Number Outstanding at end of period (in shares)	763,838
Options Outstanding - Weighted Average Remaining Contractual Life	2 years 11 months
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 25.55
Options Exercisable - Number Exercisable At end of period (in shares)	763,838
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 25.55
Stock Options | $ 30.01 – $33.36
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Number Outstanding at end of period (in shares)	4,496
Options Outstanding - Weighted Average Remaining Contractual Life	5 months
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 33.36
Options Exercisable - Number Exercisable At end of period (in shares)	4,496
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 33.36