Stock-Based Compensation - Shares Available for Grant (Details)	9 Months Ended
	Sep. 30, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Shares Available for Grant [Roll Forward]
Balance, beginning of period (in shares)	2,261,000
Options granted	(704,865)
RSAs granted (in shares)	(167,000)
Forfeited/Expired shares added back	1,098,000
Balance, end of period (in shares)	2,487,000