Investment Securities Summary of Amortized Cost and Fair Values of Corporate Debt Securities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Securities	$ 2,451,528
Corporate Debt Securities Issued by Financial Institutions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	97,058	97,883
Available-for-sale Securities, Debt Securities	98,077	96,164
Single-issuer Trust Preferred Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Trust Preferred Securities Below Investment Grade	20
Available-for-sale Debt Securities, Amortized Cost Basis	47,524	47,481
Available-for-sale Securities, Debt Securities	43,186	40,531
Subordinated Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	47,467	47,405
Available-for-sale Securities, Debt Securities	50,616	50,327
Pooled Trust Preferred Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Trust Preferred Securities Below Investment Grade	6
Available-for-sale Debt Securities, Amortized Cost Basis	2,067	2,997
Available-for-sale Securities, Debt Securities	4,275	5,306
Other Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	2,576	2,585
Available-for-sale Securities, Debt Securities	2,576	2,585
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	99,634	100,468
Available-for-sale Securities, Debt Securities	$ 100,653	$ 98,749