Fair Value of Financial Instruments (Level 3 Securities) (Details) - Recurring $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 1,629
Net unrealized gains (losses)	(77)
Ending Balance	1,552
States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	0
Net unrealized gains (losses)	0
Ending Balance	0
Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	100
Net unrealized gains (losses)
Ending Balance	100
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	647
Net unrealized gains (losses)	(15)
Ending Balance	632
Equities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	882
Net unrealized gains (losses)	(62)
Ending Balance	$ 820