Investment Securities (Maturity Schedule) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Amortized Cost
Due in one year or less, amortized cost	$ 8,393
Due after one year through five years, amortized cost	2,045
Due after ten years, amortized cost	1,753
Total, amortized cost	12,191
Mortgage-backed securities, amortized cost	408,428
Total, amortized cost	420,619
Estimated Fair Value
Due in one year or less, estimated fair value	8,467
Due after one year through five years, estimated fair value	2,070
Due after ten years, estimated fair value	2,652
Total, estimated fair value	13,189
Mortgage-backed securities, estimated fair value	389,279
Estimated fair value	402,468	414,614	[1]
Amortized Cost
Mortgage-backed securities, amortized cost	149,060
Total, amortized cost	149,060	151,795	[1]
Estimated Fair Value
Mortgage-backed securities, estimated fair value	141,002
Estimated fair value	$ 141,002	$ 141,125	[1]

[1] Derived from audited consolidated financial statements