Stock Based Compensation and Other Benefit Plans - Time-vested Restricted Stock (Details)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Restricted stock [Member]
Outstanding at beginning of period (in shares) | shares	595,535
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 8.45
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares	98,714
Estimated fair value at date of grant (in dollars per share) | $ / shares	$ 7.80
Vested (in shares) | shares	(521,379)
Vested (in dollars per share) | $ / shares	$ 8.70
Forfeited (in shares) | shares	(4,156)
Forfeited (in dollars per share) | $ / shares	$ 11.20
Outstanding at the end of period (in shares) | shares	168,714
Outstanding at the end of period (in dollars per share) | $ / shares	$ 7.24
Restricted Stock Units (RSUs) [Member]
Outstanding at beginning of period (in shares) | shares	2,183,029
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 5.82
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares	768,661
Estimated fair value at date of grant (in dollars per share) | $ / shares	$ 7.83
Vested (in shares) | shares	(815,289)
Vested (in dollars per share) | $ / shares	$ 6.36
Forfeited (in shares) | shares	(145,764)
Forfeited (in dollars per share) | $ / shares	$ 5.72
Outstanding at the end of period (in shares) | shares	1,990,637
Outstanding at the end of period (in dollars per share) | $ / shares	$ 6.38