Long-term Incentive Compensation (Summary of Liability-Classified Performance Cash Awards ) (Details) - Performance units shares in Thousands	6 Months Ended
	Jun. 30, 2021 $ / shares shares
Number of Units
Beginning balance (in shares) | shares	8,699
Granted (in shares) | shares	3,580
Vested (in shares) | shares	(2,020)
Forfeited (in shares) | shares	(622)
Ending balance (in shares) | shares	9,637
Weighted Average Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 2.57
Granted (in dollars per share) | $ / shares	4.14
Vested (in dollars per share) | $ / shares	4.05
Forfeited (in dollars per share) | $ / shares	2.98
Ending balance (in dollars per share) | $ / shares	$ 3.38