Investments (Schedule of Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturities) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Investments [Line Items]
Due in one year or less, Amortized Cost	$ 82,681
Due after one year through five years, Amortized Cost	272,930
Due after five years through ten years, Amortized Cost	99,094
Due after ten years, Amortized Cost	56,861
Debt securities, available-for-sale, cost (in dollars)	567,989	$ 538,629
Due in one year or less, Fair Value	82,667
Due after one year through five years, Fair Value	274,259
Due after five years through ten years, Fair Value	98,222
Due after ten years, Fair Value	57,398
Debt Securities, Fair Value	569,271	531,325
Mortgage Backed [Member]
Schedule of Investments [Line Items]
Debt securities, available-for-sale, cost (in dollars)	56,423
Debt Securities, Fair Value	$ 56,725	$ 59,383