Fair Value Measurements (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Goodwill impairment charges	$ 86,000	$ 391,000
Money market funds | Restricted cash and cash equivalents
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Settlement funds	$ 69,100		$ 86,900
Discount rate | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discount rate applied	0.095
Discount rate | Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discount rate applied	0.150
Discount rate | Weighted average
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discount rate applied	0.117