Loans Receivable, Net Summary of Loans Receivable (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Summary of Loans Receivable
Loans receivable	$ 4,687,669,000	$ 4,488,095,000
Allowance for loan and lease losses	(129,856,000)	(129,753,000)
Loans receivable, net	4,557,813,000	4,358,342,000
Net deferred fees, costs, premiums, and discounts included in loans receivable	15,374,000	13,710,000
Residential Real Estate
Summary of Loans Receivable
Loans receivable	637,465,000	611,463,000
Allowance for loan and lease losses	(15,131,000)	(14,680,000)
Commercial Real Estate
Summary of Loans Receivable
Loans receivable	2,418,843,000	2,337,548,000
Allowance for loan and lease losses	(67,327,000)	(67,799,000)
Other Commercial
Summary of Loans Receivable
Loans receivable	1,007,173,000	925,900,000
Allowance for loan and lease losses	(31,515,000)	(30,891,000)
Total Commercial Loans
Summary of Loans Receivable
Loans receivable	3,426,016,000	3,263,448,000
Home Equity
Summary of Loans Receivable
Loans receivable	402,970,000	394,670,000
Allowance for loan and lease losses	(9,519,000)	(9,963,000)
Other Consumer
Summary of Loans Receivable
Loans receivable	221,218,000	218,514,000
Allowance for loan and lease losses	(6,364,000)	(6,420,000)
Total Consumer and Other Loans
Summary of Loans Receivable
Loans receivable	$ 624,188,000	$ 613,184,000

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

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