Stock-Based Compensation - Schedule of Grants (Details) - shares		Jun. 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)		1,179,304
Options and RSUs Exercised (in shares)		3,952,149
Available Shares (in shares)		2,150,152
Total (in shares)		7,545,851
2017 ECP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding (in shares)		0
RSUs Outstanding (in shares)		104,167
Options and RSUs Exercised (in shares)		20,833
Available Shares (in shares)		1,875,000
Total (in shares)		2,000,000
2010 ECP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding (in shares)		250,498
RSUs Outstanding (in shares)		1,075,137
Options and RSUs Exercised (in shares)		2,981,231
Available Shares (in shares)		275,152
Total (in shares)		4,582,018
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