Share and Incentive Based Compensation - Awards Activity (Details)	6 Months Ended
	Jun. 30, 2018 $ / shares shares
Number of Units
Unvested performance units beginning balance	49,000
Granted (in units)	0
Vested (in units)	(48,000)
Forfeited / canceled (in units)	(1,000)
Unvested performance units ending balance	0
Fair Value per Unit at June 30, 2018
Unvested performance units outstanding (in usd per unit) | $ / shares	$ 0
Restricted Stock
Number of Shares/Units
Unvested shares outstanding at beginning of period	1,105,000
Granted (in shares)	5,000
Vested (in shares)	(1,049,000)
Forfeited / Canceled (in shares)	(36,000)
Unvested shares outstanding at end of period	25,000
Fair Value (usd per share)
Unvested shares outstanding at beginning of period (in usd per share) | $ / shares	$ 22.62
Granted (in usd per share) | $ / shares	15.15
Vested (in usd per share) | $ / shares	22.71
Forfeited / Canceled (in usd per share) | $ / shares	22.11
Unvested shares outstanding at end of period (in usd per share) | $ / shares	$ 18.34
Performance Share Units
Number of Shares/Units
Unvested shares outstanding at beginning of period	183,000
Granted (in shares)	0
Vested (in shares)	(177,000)
Forfeited / Canceled (in shares)	(6,000)
Unvested shares outstanding at end of period	0
Fair Value (usd per share)
Unvested shares outstanding at end of period (in usd per share) | $ / shares	$ 0