Fair Value Measurement (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	$ 199,087		$ 255,201
Mortgage servicing rights	50,001		48,152
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	199,087		255,201
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	196,570		249,195
Loans	157,270	[1]	178,669	[1]
Mortgage servicing rights	50,001		48,152
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	196,570		249,195
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	157,270	[1]	178,669	[1]
Mortgage servicing rights	$ 50,001		$ 48,152

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