Share-Based Compensation - Unvested Restricted Shares (Details)	6 Months Ended
	Jun. 30, 2020 $ / shares shares
Restricted Shares
Nonvested Restricted Shares
Unvested, beginning balance (in shares) | shares	35,630
Granted (in shares) | shares	169,781
Vested (in shares) | shares	(200,223)
Forfeited (in shares) | shares	(1,781)
Unvested, ending balance (in shares) | shares	3,407
Weighted Avg. Grant Date Fair Value
Unvested, beginning balance (in dollars per share) | $ / shares	$ 63.27
Granted (in dollars per share) | $ / shares	9.15
Vested (in dollars per share) | $ / shares	40.69
Forfeited (in dollars per share) | $ / shares	58.01
Unvested, ending balance (in dollars per share) | $ / shares	$ 59.87
Share-Settled RSUs
Nonvested Restricted Shares
Unvested, beginning balance (in shares) | shares	1,125,346
Granted (in shares) | shares	1,511,307
Vested (in shares) | shares	(289,074)
Forfeited (in shares) | shares	(339,120)
Unvested, ending balance (in shares) | shares	2,008,459
Weighted Avg. Grant Date Fair Value
Unvested, beginning balance (in dollars per share) | $ / shares	$ 37.91
Granted (in dollars per share) | $ / shares	7.83
Vested (in dollars per share) | $ / shares	41.39
Forfeited (in dollars per share) | $ / shares	34.93
Unvested, ending balance (in dollars per share) | $ / shares	$ 27.60
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	(264,471)
Unvested, ending balance (in shares) | shares	548,416
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	28.91
Unvested, ending balance (in dollars per share) | $ / shares	$ 36.15