Loans Receivable, Net Summary of Loans Receivable (Details) - USD ($)		Jun. 30, 2015	Dec. 31, 2014
Summary of Loans Receivable
Loans receivable	[1]	$ 4,807,431,000	$ 4,488,095,000
Allowance for loan and lease losses		(130,519,000)	(129,753,000)
Loans receivable, net		4,676,912,000	4,358,342,000
Net deferred fees, costs, premiums, and discounts included in loans receivable		13,312,000	13,710,000
Residential Real Estate
Summary of Loans Receivable
Loans receivable		635,674,000	611,463,000
Allowance for loan and lease losses		(14,850,000)	(14,680,000)
Commercial Real Estate
Summary of Loans Receivable
Loans receivable		2,454,369,000	2,337,548,000
Allowance for loan and lease losses		(68,697,000)	(67,799,000)
Other Commercial
Summary of Loans Receivable
Loans receivable		1,074,905,000	925,900,000
Allowance for loan and lease losses		(31,483,000)	(30,891,000)
Total Commercial
Summary of Loans Receivable
Loans receivable		3,529,274,000	3,263,448,000
Home Equity
Summary of Loans Receivable
Loans receivable		410,708,000	394,670,000
Allowance for loan and lease losses		(8,946,000)	(9,963,000)
Other Consumer
Summary of Loans Receivable
Loans receivable		231,775,000	218,514,000
Allowance for loan and lease losses		(6,543,000)	(6,420,000)
Total Consumer and Other
Summary of Loans Receivable
Loans receivable		$ 642,483,000	$ 613,184,000

[1] Includes net deferred fees, costs, premiums and discounts of $13,312,000 and $13,710,000 at June 30, 2015 and December 31, 2014, respectively.