Disclosures about fair value of assets and liabilities (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Hedged loans [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	$ (59,911)
Reason for Transfer (a)	Valuation determined by widely accepted techniques including discounted cash flow analysis on expected cash flows of each derivative and observable market rate inputs such as yield curves and contractual terms on each instrument.
Forward sale commitments [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	(510)
Reason for Transfer (b)	Valuation determined by quoted prices for similar loans in the secondary market with an expected fallout rate (interest rate locked pipeline loans not expected to close). Fallout rate is not considered a significant input to the fair value in its entirety.
Interest rate swap agreements [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	6,464
Reason for Transfer (a)	Valuation determined by widely accepted techniques including discounted cash flow analysis on expected cash flows of each derivative and observable market rate inputs such as yield curves and contractual terms on each instrument.
Commitments to originate loans [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	71
Reason for Transfer (b)	Valuation determined by quoted prices for similar loans in the secondary market with an expected fallout rate (interest rate locked pipeline loans not expected to close). Fallout rate is not considered a significant input to the fair value in its entirety.
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedged loans [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Forward sale commitments [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Interest rate swap agreements [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Commitments to originate loans [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Significant Other Observable Inputs (Level 2) [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	53,886
Significant Other Observable Inputs (Level 2) [Member] | Hedged loans [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	59,911
Significant Other Observable Inputs (Level 2) [Member] | Forward sale commitments [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	510
Significant Other Observable Inputs (Level 2) [Member] | Interest rate swap agreements [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	(6,464)
Significant Other Observable Inputs (Level 2) [Member] | Commitments to originate loans [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3	(71)
Significant Unobservable Inputs (Level 3) [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Significant Unobservable Inputs (Level 3) [Member] | Hedged loans [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Significant Unobservable Inputs (Level 3) [Member] | Forward sale commitments [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Significant Unobservable Inputs (Level 3) [Member] | Interest rate swap agreements [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3
Significant Unobservable Inputs (Level 3) [Member] | Commitments to originate loans [Member]
Transfers between Levels 1, 2 and 3
Transfers out to Level 1, 2, and 3