Stock-Based Compensation - Schedule of Grants (Details) - shares		Sep. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding (in shares)		264,246	264,246
RSUs Outstanding (in shares)		1,643,949
Options and RSUs Exercised (in shares)		4,372,668
Available Shares (in shares)		1,664,988
Total (in shares)		7,945,851
2017 ECP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding (in shares)		0
RSUs Outstanding (in shares)		733,500
Options and RSUs Exercised (in shares)		41,664
Available Shares (in shares)		1,374,836
Total (in shares)		2,150,000
2010 ECP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding (in shares)		250,498
RSUs Outstanding (in shares)		910,449
Options and RSUs Exercised (in shares)		3,380,919
Available Shares (in shares)		290,152
Total (in shares)		4,832,018
2005 LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding (in shares)	[1]	13,748
RSUs Outstanding (in shares)	[1]	0
Options and RSUs Exercised (in shares)	[1]	950,085
Available Shares (in shares)	[1]	0
Total (in shares)	[1]	963,833

[1] Expired June 2015