Share-Based Compensation - Restricted Stock Unit Activity (Details)	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Restricted Stock Units (RSUs)
Shares
Outstanding and unvested at beginning of period (in shares) | shares	1,183,500
Granted (in shares) | shares	0
Vested (in shares) | shares	(5,325)
Forfeited (in shares) | shares	(20,760)
Outstanding and unvested at end of period (in shares) | shares	1,157,415
Weighted- Average Grant Date Fair Value
Outstanding and unvested at beginning of period (in dollars per share) | $ / shares	$ 2.50
Granted (in dollars per share) | $ / shares	0.00
Vested (in dollars per share) | $ / shares	2.35
Forfeited (in dollars per share) | $ / shares	2.35
Outstanding and unvested at end of period (in dollars per share) | $ / shares	$ 2.50
Performance-Based Restricted Stock Units (PBRSUs)
Shares
Outstanding and unvested at beginning of period (in shares) | shares	4,785,900
Granted (in shares) | shares	245,868
Vested (in shares) | shares	0
Forfeited (in shares) | shares	(768,741)
Outstanding and unvested at end of period (in shares) | shares	4,263,027
Weighted- Average Grant Date Fair Value
Outstanding and unvested at beginning of period (in dollars per share) | $ / shares	$ 3.37
Granted (in dollars per share) | $ / shares	9.93
Vested (in dollars per share) | $ / shares	0.00
Forfeited (in dollars per share) | $ / shares	4.00
Outstanding and unvested at end of period (in dollars per share) | $ / shares	$ 3.64