Share-Based Compensation - Changes in Number of Non-Employee Warrants (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Exercised (in shares)	(1,470,323)	(1,533,616)	(3,175,843)
BSA
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Beginning balance, options (in shares)	154,910	199,408	542,148
Options granted (in shares)	48,655	38,070	5,040
Exercised (in shares)	(37,000)	(34,568)	(345,780)
Forfeited (in shares)	21,560	(48,000)	(2,000)
Ending balance, options (in shares)	188,125	154,910	199,408