Investment Securities (Maturity Schedule) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Amortized Cost
Due in one year or less, amortized cost	$ 8,395
Due after one year through five years, amortized cost	2,040
Total, amortized cost	10,435
Mortgage-backed securities, amortized cost	399,280
Total, amortized cost	409,715
Estimated Fair Value
Due in one year or less, estimated fair value	8,445
Due after one year through five years, estimated fair value	2,064
Total, estimated fair value	10,509
Mortgage-backed securities, estimated fair value	388,601
Estimated fair value	399,110	414,614	[1]
Amortized Cost
Mortgage-backed securities, amortized cost	147,055
Total, amortized cost	147,055	151,795	[1]
Estimated Fair Value
Mortgage-backed securities, estimated fair value	142,288
Estimated fair value	$ 142,288	$ 141,125	[1]

[1] Derived from audited consolidated financial statements