Equity Compensation (Stock Options Outstanding by Exercise Price) (Details) - $ / shares	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 18.73	$ 18.78
$ 12.15 – $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)	12.15
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)	1,853,679
Options Outstanding - Weighted Average Remaining Contractual Life	3 years 3 months 18 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 18.73
Options Exercisable - Number Exercisable At end of period (in shares)	1,322,519
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 21.38
Stock Options | $ 12.15 – $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)	798,284
Options Outstanding - Weighted Average Remaining Contractual Life	6 years 3 months 18 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 12.77
Options Exercisable - Number Exercisable At end of period (in shares)	267,124
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 13.99
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)	713,476
Options Outstanding - Weighted Average Remaining Contractual Life	1 year
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 22.20
Options Exercisable - Number Exercisable At end of period (in shares)	713,476
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 22.20
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)	337,423
Options Outstanding - Weighted Average Remaining Contractual Life	1 year 1 month 6 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 25.33
Options Exercisable - Number Exercisable At end of period (in shares)	337,423
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 25.33
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	1 year 10 months 24 days
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