Investments (Schedule of Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Due in one year or less, Amortized Cost	$ 58,034
Due after one year through five years, Amortized Cost	211,191
Due after five years through ten years, Amortized Cost	102,571
Due after ten years, Amortized Cost	59,041
Debt securities, available-for-sale, cost (in dollars)	497,251	$ 450,770
Due in one year or less, Fair Value	58,030
Due after one year through five years, Fair Value	210,938
Due after five years through ten years, Fair Value	100,018
Due after ten years, Fair Value	59,106
Debt Securities, Fair Value	494,054	450,785
Mortgage Backed [Member]
Schedule of Investments [Line Items]
Debt securities, available-for-sale, cost (in dollars)	66,414
Debt Securities, Fair Value	$ 65,962	$ 52,060