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Equity Compensation and Other Benefit Plans - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
RSUs With Service Condition
RSUs With Service Condition
Outstanding at beginning of year (in shares)	1,829,455	1,379,681	1,206,446
Granted (in shares)	1,517,069	939,046	461,525
Settled (in shares)	(497,974)	(379,272)	(269,290)
Cancelled, forfeited or expired (in shares)	0	(110,000)	(19,000)
Outstanding at end of year (in shares)	2,848,550	1,829,455	1,379,681
RSUs vested but not settled at end of year (in shares)	1,142,900	1,160,416	809,681
RSUs unvested at end of year (in shares)	1,705,650	669,039	570,000
Weighted Average Grant Date Fair Value
Outstanding at beginning of year (in dollars per share)	$ 6.19	$ 7.62	$ 7.57
Granted (in dollars per share)	4.16	4.88	7.35
Settled (in dollars per share)	6.49	7.75	6.93
Cancelled/forfeited (in dollars per share)	0	7.59	7.72
Outstanding at end of year (in dollars per share)	5.05	6.19	7.62
RSUs vested but not settled at end of year (in dollars per share)	5.22	5.37	7.70
Weighted average grant date fair value (in dollars per share)	$ 4.94	$ 7.61	$ 7.50
RSUs With Market and Service Conditions
RSUs With Service Condition
Outstanding at beginning of year (in shares)	1,623,174	1,301,250	1,151,250
Granted (in shares)	2,408,520	763,174	451,000
Settled (in shares)	(409,000)	(441,250)	(290,000)
Cancelled, forfeited or expired (in shares)	0	0	(11,000)
Outstanding at end of year (in shares)	3,622,694	1,623,174	1,301,250
RSUs vested but not settled at end of year (in shares)	451,000	409,000	441,250
RSUs unvested at end of year (in shares)	3,171,694	1,214,174	860,000
Weighted Average Grant Date Fair Value
Outstanding at beginning of year (in dollars per share)	$ 6.26	$ 6.78	$ 6.21
Granted (in dollars per share)	3.40	5.50	6.97
Settled (in dollars per share)	6.91	6.48	4.81
Cancelled/forfeited (in dollars per share)	0	0	6.71
Outstanding at end of year (in dollars per share)	4.29	6.26	6.78
RSUs vested but not settled at end of year (in dollars per share)	6.97	6.91	6.48
Weighted average grant date fair value (in dollars per share)	$ 3.90	$ 6.04	$ 6.94
Expected term	1 year
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 12.3	$ 6.8
Period for recognizing unrecognized compensation cost	1 year 9 months 18 days
RSUs With Service Condition
Outstanding at beginning of year (in shares)	3,452,629	2,680,931	2,357,696
Granted (in shares)	3,925,589	1,702,220	912,525
Settled (in shares)	(906,974)	(820,522)	(559,290)
Cancelled, forfeited or expired (in shares)	0	(110,000)	(30,000)
Outstanding at end of year (in shares)	6,471,244	3,452,629	2,680,931
RSUs vested but not settled at end of year (in shares)	1,593,900	1,569,416	1,250,931
RSUs unvested at end of year (in shares)	4,877,344	1,883,213	1,430,000
Weighted Average Grant Date Fair Value
Outstanding at beginning of year (in dollars per share)	$ 6.22	$ 7.21	$ 6.90
Granted (in dollars per share)	3.69	5.16	7.16
Settled (in dollars per share)	6.68	7.07	5.83
Cancelled/forfeited (in dollars per share)	0	7.59	7.35
Outstanding at end of year (in dollars per share)	4.62	6.22	7.21
RSUs vested but not settled at end of year (in dollars per share)	5.72	5.77	7.27
Weighted average grant date fair value (in dollars per share)	$ 4.27	$ 6.60	$ 7.16
RSUs with Service Condition, weighted average grant date fair value based on share closing price
RSUs With Service Condition
Granted (in shares)	2,485,124	452,585	160,025
Weighted Average Grant Date Fair Value
Weighted average volatility estimated	48.00%
Expected term	3 years
Weighted average risk-free rate	0.17%
Share price (dollars per share)		$ 2.32	$ 7.28
RSUs With Service Condition, Weighted Average Grant Date Fair Value Based on Share Closing Price
RSUs With Service Condition
Granted (in shares)	1,224,507	44,922
Weighted Average Grant Date Fair Value
Weighted average volatility estimated	54.00%
Expected term	2 years 6 months
Weighted average risk-free rate	0.36%
Share price (dollars per share)		$ 2.56
Remaining RSUs With Service Condition, Weighted Average Grant Date Fair Value Based on Share Closing Price
RSUs With Service Condition
Granted (in shares)	215,958
Weighted Average Grant Date Fair Value
Share price (dollars per share)	$ 4.70
RSUs with Service Condition and both Service and Market Conditions
RSUs With Service Condition
Granted (in shares)		1,204,713	752,500
Weighted Average Grant Date Fair Value
Weighted average volatility estimated		14.00%	15.00%
Expected term		3 years	3 years
Weighted average risk-free rate		1.36%	2.47%

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