Income Taxes - Operating loss and credit carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Federal
Operating loss carryforwards
Net operating loss carryforwards	$ 2,216	$ 2,997
Federal \| 2030
Operating loss carryforwards
Net operating loss carryforwards	9,072	9,828
Illinois \| 2031
Operating loss carryforwards
Net operating loss carryforwards	$ 266,061	$ 250,723

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32559-109319

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant