Commitments, Off-Balance Sheet Arrangements and Contingent Liabilities (Details Textuals) (USD $)	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Standby letters of credit Fair value	$ 3,542,000	[1]	$ 3,754,000	[1]
Commitment on standby letters of credit	353,000,000		371,000,000
Carrying value of investments	27,000,000		33,000,000
Commitments under unconsolidated projects	28,000,000		16,000,000
Residential mortgage loans sold with recourse risk	46,000,000		56,000,000
Residential mortgage loans sold with credit recourse risk	178,000,000		233,000,000
Loans sold to outside investors original amount	18,700,000,000
Loans sold to outside investors remaining outstanding amount	7,600,000,000
Loans repurchased under make whole requests	5,000,000		3,000,000
Loss reimbursement claims under make whole requests	734,000		3,000,000
Mortgage Repurchase Reserve [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Balance at end of period	3,258,000		5,737,000		3,300,000
Reserve for Off-balance Sheet Activities [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Balance at end of period	$ 24,900,000		$ 21,900,000		$ 21,800,000	$ 14,700,000

[1] (1) The commitment on standby letters of credit was $353 million and $371 million at December 31, 2014 and 2013, respectively. See Note 15 for additional information on the standby letters of credit and for information on the fair value of lending-related commitments.