Fair Value of Financial Instruments (Level 3 Securities) (Details) - Recurring $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 1,511
Net unrealized gains (losses)	35
Ending Balance	1,546
Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	250
Net unrealized gains (losses)	0
Ending Balance	250
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	666
Net unrealized gains (losses)	35
Ending Balance	701
Equities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	595
Net unrealized gains (losses)	0
Ending Balance	$ 595