Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	$ 174,279		$ 265,914
Mortgage servicing rights	52,078		45,949
Fair Value, Inputs, Level 1 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	0		0
Fair Value, Inputs, Level 2 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	174,279		265,914
Fair Value, Inputs, Level 3 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	0		0
Fair Value, Measurements, Nonrecurring [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	173,389		261,410
Loans	111,337	[1]	115,741	[1]
Mortgage servicing rights	52,078		45,949
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	0		0
Loans	0	[1]	0	[1]
Mortgage servicing rights	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	173,389		261,410
Loans	0	[1]	0	[1]
Mortgage servicing rights	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	0		0
Loans	111,337	[1]	115,741	[1]
Mortgage servicing rights	$ 52,078		$ 45,949

[1] (1)        Represents individually evaluated impaired loans, net of the related allowance for loan losses.