Income Taxes - Net Operating Loss Carryforwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards
Deferred tax assets, valuation allowance	$ 79,289	$ 73,477
Deferred tax asset, change in valuation allowance amount	5,800	5,900
Uncertain income tax positions recorded	0	0
Federal
Operating Loss Carryforwards
Net operating loss (“NOL”) carryforwards	255,600	220,100
State
Operating Loss Carryforwards
Net operating loss (“NOL”) carryforwards	$ 94,800	$ 77,800
State | Earliest Tax Year
Operating Loss Carryforwards
Operating loss carryforwards expiration year	2020
State | Latest Tax Year
Operating Loss Carryforwards
Operating loss carryforwards expiration year	2039