Stock Compensation Plans and Share-Based Compensation Awards - RSU (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stock Compensation Plans and Share-Based Compensation Awards
Share-based compensation expense	$ 2,977	$ 52,134	$ 4,822	$ 52,134
RSUs
Stock Compensation Plans and Share-Based Compensation Awards
Share-based compensation expense	1,400	$ 200	2,100	$ 200
Unrecognized compensation expense	$ 17,400		$ 17,400
Vesting period			4 years
Weighted average period outstanding for unvested RSUs			3 years 3 months 18 days
Number outstanding
Balance at beginning of period (in shares)			506
Granted (in shares)			501
Vested (in shares)			(131)
Forfeited (in shares)			(26)
Balance at end of period (in shares)	850		850
Weighted average grant date fair value
Balance at beginning of period (in dollars per share)			$ 16.30
Granted (in dollars per share)			26.12
Vested (in dollars per share)			16.00
Forfeited (in dollars per share)			19.82
Balance at end of period (in dollars per share)	$ 22.04		$ 22.04