Share-based Compensation - Summary of Restricted Stock Outstanding (Details) - Restricted stock shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Shares
Non-vested at beginning of the year (in shares) | shares	9,104
Granted (in shares) | shares	1,868
Vested (in shares) | shares	(173)
Forfeited | shares	3,668
Non-vested at end of the year (in shares) | shares	7,131
Weighted Average Grant Date Fair Value Per Share
Non-vested at beginning of the year (in dollars per share) | $ / shares	$ 10.15
Granted (in dollars per share) | $ / shares	7.29
Vested (in dollars per share) | $ / shares	7.76
Forfeited (in dollars per share) | $ / shares	10.17
Non-vested at end of the year (in dollars per share) | $ / shares	$ 9.44