Income Taxes – Continuing Operations - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation
Tax at federal statutory rate (as a percent)	21.00%	21.00%
State income taxes (as a percent)	(114.80%)	4.00%
Foreign taxes (as a percent)	(51.90%)	(0.10%)
Tax benefit for U.K. sale	345.20%	17.50%
Valuation allowance (as a percent)	(474.70%)	(13.50%)
Unrecognized tax benefits (as a percent)	(34.50%)	(4.80%)
Tax credits (as a percent)	(108.40%)	2.50%
Deferred tax impact of enacted tax rate and law changes (as a percent)		(0.70%)
Permanent items (as a percent)	(120.60%)	(1.80%)
Other (as a percent)	0.10%	(1.40%)
Effective income tax rate (as a percent)	(538.60%)	22.70%