Long-term Incentive Compensation (Summary of Equity-Classified Stock Option Activity) (Details) - Stock options shares in Thousands	6 Months Ended
	Jun. 30, 2021 $ / shares shares
Number of Options
Beginning balance (in shares) | shares	3,850
Granted (in shares) | shares	0
Exercised (in shares) | shares	0
Forfeited or expired (in shares) | shares	(151)
Ending balance (in shares) | shares	3,699
Exercisable (in shares) | shares	3,699
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 13.39
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	0
Forfeited or expired (in dollars per share) | $ / shares	32.21
Ending balance (in dollars per share) | $ / shares	12.63
Exercisable (in dollars per share) | $ / shares	$ 12.63