Employee Stock Compensation Plans - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Total unrecognized compensation	$ 26,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 8.07	$ 9.80
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.50%	2.50%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	34.79%	34.88%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	3 years 10 months 24 days	3 years 9 months 18 days
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, Beginning balance, Shares Under Option (in shares)	2,606
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	2,131
Vested, Shares Under Option (in shares)	(99)
Outstanding, Ending balance, Shares Under Option (in shares)	4,559	2,606
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period	79
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, Beginning balance, Weighted Average Exercise Price per Share (in dollars per share)		$ 29.08
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price		26.45
Vested, Weighted Average Exercise Price per Share (in dollars per share)		16.07
Outstanding, Ending balance, Weighted Average Exercise Price per Share (in dollars per share)	$ 28.08		$ 29.08
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price		$ 32.57
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, Weighted Average Remaining Contratual Term (in years)	5 years 7 months 13 days
Outstanding, Aggregate Intrinsic Value	$ 32,300
Exercisable, Shares Under Option (in shares)	699
Exercisable, Weighted Average Exercise Price per Share (in dollars per share)	$ 27.99
Exercisable, Weighted Average Remaining Contractual Term (in years)	4 years 8 months 1 day
Exercisable, Aggregate Intrinsic Value	$ 5,010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Fully vested and expected to vest, Shares Under Option (in shares)	3,860
Fully vested and expected to vest, Weighted Average Exercise Price per Share (in dollars per share)	$ 28.09
Fully vested and expected to vest, Weighted Average Remaining Contractual Term (in years)	5 years 9 months 14 days
Fully vested and expected to vest, Aggregate Intrinsic Value	$ 27,300
Total intrinsic value of all options exercised	1,000	$ 4,000	$ 3,000
Cash received from option exercises	2,000	$ 4,000	2,000
Share-based Payment Arrangement, Exercise of Option, Tax Benefit	$ 0		$ 1,000
Total unrecognized compensation cost, period of recognition	1 year 4 months 24 days
Stock Options [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Vesting period	1 year
Stock Options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Vesting period	10 years