Loans Receivable, Net Summary of Loans Receivable (Details) - USD ($)		Dec. 31, 2015	Dec. 31, 2014
Summary of Loans Receivable
Loans receivable	[1]	$ 5,078,681,000	$ 4,488,095,000
Allowance for loan and lease losses		(129,697,000)	(129,753,000)
Loans receivable, net		$ 4,948,984,000	$ 4,358,342,000
Weighted Average Interest Rate on Loans		4.84%	4.86%
Net deferred fees, costs, premiums, and discounts included in loans receivable		$ 15,529,000	$ 13,710,000
Residential Real Estate
Summary of Loans Receivable
Loans receivable		688,912,000	611,463,000
Allowance for loan and lease losses		(14,427,000)	(14,680,000)
Commercial Real Estate
Summary of Loans Receivable
Loans receivable		2,633,953,000	2,337,548,000
Allowance for loan and lease losses		(67,877,000)	(67,799,000)
Other Commercial
Summary of Loans Receivable
Loans receivable		1,099,564,000	925,900,000
Allowance for loan and lease losses		(32,525,000)	(30,891,000)
Total Commercial
Summary of Loans Receivable
Loans receivable		3,733,517,000	3,263,448,000
Home Equity
Summary of Loans Receivable
Loans receivable		420,901,000	394,670,000
Allowance for loan and lease losses		(8,998,000)	(9,963,000)
Other Consumer
Summary of Loans Receivable
Loans receivable		235,351,000	218,514,000
Allowance for loan and lease losses		(5,870,000)	(6,420,000)
Total Consumer and Other
Summary of Loans Receivable
Loans receivable		$ 656,252,000	$ 613,184,000

[1] Includes net deferred fees, costs, premiums and discounts of $15,529,000 and $13,710,000 at December 31, 2015 and 2014, respectively.