Long-term Incentive Compensation (Summary of Liability-Classified Restricted Stock Unit Activity) (Details) - Restricted stock units shares in Thousands	6 Months Ended
	Jun. 30, 2021 $ / shares shares
Number of Units
Beginning balance (in shares) | shares	11,613
Granted (in shares) | shares	1,486
Vested (in shares) | shares	(4,522)
Forfeited (in shares) | shares	(489)
Ending balance (in shares) | shares	8,088
Weighted Average Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 2.67
Granted (in dollars per share) | $ / shares	4.23
Vested (in dollars per share) | $ / shares	3.40
Forfeited (in dollars per share) | $ / shares	4.37
Ending balance (in dollars per share) | $ / shares	$ 4.90