Loan Servicing Principal Balance of Loans Serviced for Others (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Capitalization Rate for Residental Loan Servicing Portfolio	0.70%	0.00%
Balance of loans serviced for others	$ 5,249,255	$ 4,309,283
Residential Mortgage
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Balance of loans serviced for others	4,132,570	2,915,817
Commercial Real Estate
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Balance of loans serviced for others	983,782	1,276,742
Commercial
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Balance of loans serviced for others	$ 132,903	$ 116,724