Summary of Significant Accounting Policies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Real Estate, Foreclosed Assets, and Repossessed Assets [Abstract]
Other Real Estate, Foreclosed Assets, and Repossessed Assets	$ 1,686,000	$ 2,644
Cash and Cash Equivalents [Abstract]
Cash on deposit with Federal Reserve Bank	636,345,000	631,562,000
Compensating balances with Federal Reserve Bank	10,031,000	7,507,000
Loans and Leases Receivable Disclosure [Abstract]
Mortgage loans held for sale	52,875,000	40,828,000
Impairment losses	806,000	102,000	$ 616,000
Write-downs of OREO	207,000	224,000	3,512,000
Federal Home Loan Bank Stock and Federal Reserve Bank Stock [Abstract]
Federal Reserve Bank stock	16,421,000	16,187,000
Federal Home Loan Bank stock	10,135,000	10,662,000
Advertising expense	3,452,000	3,734,000	3,532,000
Share-based Compensation [Abstract]
Stock compensation expense	3,959,000	3,634,000	2,936,000
Tax benefits from stock-based compensation	$ 1,443,000	$ 1,390,000	$ 1,122,000