Share-Based Compensation - Unvested Restricted Shares (Details)	9 Months Ended
	Sep. 30, 2020 $ / shares shares
Restricted Stock
Nonvested Restricted Shares
Unvested, beginning balance (in shares) | shares	35,630
Granted (in shares) | shares	174,347
Vested (in shares) | shares	(205,822)
Forfeited (in shares) | shares	(1,781)
Unvested, ending balance (in shares) | shares	2,374
Weighted Avg. Grant Date Fair Value
Unvested, beginning balance (in dollars per share) | $ / shares	$ 63.27
Granted (in dollars per share) | $ / shares	9.10
Vested (in dollars per share) | $ / shares	40.64
Forfeited (in dollars per share) | $ / shares	58.01
Unvested, ending balance (in dollars per share) | $ / shares	$ 61.36
Share-Settled RSUs
Nonvested Restricted Shares
Unvested, beginning balance (in shares) | shares	1,125,346
Granted (in shares) | shares	1,511,628
Vested (in shares) | shares	(447,292)
Forfeited (in shares) | shares	(371,271)
Unvested, ending balance (in shares) | shares	1,818,411
Weighted Avg. Grant Date Fair Value
Unvested, beginning balance (in dollars per share) | $ / shares	$ 37.91
Granted (in dollars per share) | $ / shares	7.86
Vested (in dollars per share) | $ / shares	41.39
Forfeited (in dollars per share) | $ / shares	35.11
Unvested, ending balance (in dollars per share) | $ / shares	$ 28.49
PSUs
Nonvested Restricted Shares
Unvested, beginning balance (in shares) | shares	806,233
Granted (in shares) | shares	6,654
Vested (in shares) | shares	0
Forfeited (in shares) | shares	(275,514)
Unvested, ending balance (in shares) | shares	537,373
Weighted Avg. Grant Date Fair Value
Unvested, beginning balance (in dollars per share) | $ / shares	$ 34.12
Granted (in dollars per share) | $ / shares	12.26
Vested (in dollars per share) | $ / shares	0
Forfeited (in dollars per share) | $ / shares	28.75
Unvested, ending balance (in dollars per share) | $ / shares	$ 36.33