Loans Receivable, Net Summary of Loans Receivable (Details) - USD ($)		Mar. 31, 2016	Dec. 31, 2015
Summary of Loans Receivable
Loans receivable	[1]	$ 5,197,193,000	$ 5,078,681,000
Allowance for loan and lease losses		(130,071,000)	(129,697,000)
Loans receivable, net		$ 5,067,122,000	$ 4,948,984,000
Weighted Average Interest Rate on Loans		4.81%	4.84%
Net deferred fees, costs, premiums, and discounts included in loans receivable		$ 14,010,000	$ 15,529,000
Residential Real Estate
Summary of Loans Receivable
Loans receivable		685,026,000	688,912,000
Allowance for loan and lease losses		(13,196,000)	(14,427,000)
Commercial Real Estate
Summary of Loans Receivable
Loans receivable		2,680,691,000	2,633,953,000
Allowance for loan and lease losses		(67,046,000)	(67,877,000)
Other Commercial
Summary of Loans Receivable
Loans receivable		1,172,956,000	1,099,564,000
Allowance for loan and lease losses		(36,054,000)	(32,525,000)
Total Commercial
Summary of Loans Receivable
Loans receivable		3,853,647,000	3,733,517,000
Home Equity
Summary of Loans Receivable
Loans receivable		423,895,000	420,901,000
Allowance for loan and lease losses		(8,149,000)	(8,998,000)
Other Consumer
Summary of Loans Receivable
Loans receivable		234,625,000	235,351,000
Allowance for loan and lease losses		(5,626,000)	(5,870,000)
Total Consumer and Other
Summary of Loans Receivable
Loans receivable		$ 658,520,000	$ 656,252,000

[1] Includes net deferred fees, costs, premiums and discounts of $14,010,000 and $15,529,000 at March 31, 2016 and December 31, 2015, respectively.