Investments (Held-to-Maturity Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 1,523	$ 1,616
Held-to-maturity securities, unrealized gains	12	29
Held-to-maturity securities, unrealized losses	23	0
Fair Value	1,512	1,645
Mortgage backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,523	1,615
Held-to-maturity securities, unrealized gains	12	29
Held-to-maturity securities, unrealized losses	23	0
Fair Value	$ 1,512	1,644
U.S. Treasury securities and obligations of U.S. Government corporations and agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost		1
Held-to-maturity securities, unrealized gains		0
Held-to-maturity securities, unrealized losses		0
Fair Value		$ 1