Fair Value of Assets and Liabilities (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) $ / Loan	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	$ 1,724,667,000	$ 1,716,388,000
Mortgage servicing rights	19,103,000	9,092,000	$ 8,435,000	$ 8,946,000
Derivative Assets	$ 49,213,000	42,779,000
Weighted Average Pull Through Derivatives	85.50%
Mortgage loans held-for-sale	$ 418,374,000	388,038,000
Impaired loans	$ 90,516,000	101,255,000
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pull Through Rate, Derivatives	35.00%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pull Through Rate, Derivatives	100.00%
Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value inputs, discount for lack of marketability	10.00%
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	$ 1,724,667,000	1,716,388,000
Mortgage servicing rights	19,103,000	9,092,000
Principal amount outstanding on loans held-for-sale or securitization or asset-backed financing arrangement	414,400,000	372,000,000
Mortgage loans held-for-sale	418,374,000	388,038,000
Valued Using Discounted Cash Flow Model [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	26.3
Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	131,809,000	108,595,000
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	35,248,000	56,686,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	22,137,000	11,361,000
Mortgage servicing rights	19,103,000	9,092,000
Derivative Assets	56,394,000	51,298,000
Mortgage loans held-for-sale	418,374,000	388,038,000
Fair Value, Measurements, Recurring | Non-performing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held-for-sale	0	0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	22,137,000	0
Mortgage servicing rights	19,103,000	9,092,000
Derivative Assets	2,291,000	7,021,000
Mortgage loans held-for-sale	$ 0	0
Fair Value, Measurements, Recurring | Level 3 | Loans Held For Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate	9.13%
Fair Value, Measurements, Recurring | Level 3 | Loans Held For Investment | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit discount	1.00%
Fair Value, Measurements, Recurring | Level 3 | Loans Held For Investment | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit discount	3.00%
Fair Value, Measurements, Recurring | Level 3 | Loans Held For Investment | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit discount	3.03%
Fair Value, Measurements, Recurring | Level 3 | Mortgage Servicing Rights | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate	5.00%
Discount rate input	4.00%
Fair Value, Measurements, Recurring | Level 3 | Mortgage Servicing Rights | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate	80.00%
Discount rate input	8.00%
Fair Value, Measurements, Recurring | Level 3 | Mortgage Servicing Rights | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate	9.25%
Discount rate input	6.27%
Range of Inputs | $ / Loan	65.00
Weighted Average of Inputs | $ / Loan	240.00
Fair Value, Measurements, Recurring | Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	$ 131,809,000	108,595,000
Fair Value, Measurements, Recurring | Municipal | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	79,626,000	68,613,000
Fair Value, Measurements, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	35,248,000	56,686,000
Fair Value, Measurements, Recurring | Equity securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	$ 25,199,000
Nonmonetary Transaction, Gain (Loss) Recognized on Transfer	2,400,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	64,184,000
Other real estate owned	45,584,000
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	64,184,000
Other real estate owned	$ 45,584,000