Acquisitions Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		May 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned		$ 385,969	$ 385,969
Goodwill			$ 444,327	$ 212,820
Cascade Bank Acquisition, as recorded by Cascade Bank [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		246,804
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities		476,733
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		3,015,571
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Asset		32,232
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets		113,915
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Real Estate Owned		1,268
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		0
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Held for Investment		2,111,786
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Held for Sale		10,253
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans and Leases Receivable, Allowance		23,974
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		46,554
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Deposits		2,669,910
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities		62,150
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		2,732,060
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net		283,511
Cascade Bank Acquisition, Fair Value Adjustments [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities	[1]	4,876
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		25,454
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Asset	[2]	(22,336)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets	[3]	1,378
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Real Estate Owned		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	[4]	47,950
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Held for Investment	[5]	(31,703)
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Held for Sale		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans and Leases Receivable, Allowance	[6]	(23,974)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	[7]	1,315
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Deposits		(934)
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities		408
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		(526)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net		24,928
Cascade Bank Acquisition, as Recorded by the Company [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		246,804
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities		481,609
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		3,041,025
Payments to Acquire Businesses, Gross		155,029
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Asset		9,896
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets		115,293
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Real Estate Owned		1,268
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		47,950
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Held for Investment		2,080,083
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Held for Sale		10,253
Business Combination, Consideration Transferred		540,998
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans and Leases Receivable, Allowance		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		47,869
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Deposits		2,668,976
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities		62,558
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		2,731,534
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net		309,491
Goodwill		$ 231,507

[1] Write up of the book value of investments to their estimated fair values on the date of acquisition based upon quotes obtained from an independent third party pricing service.

[2] Adjustment consists of the write-off of pre-existing deferred tax assets as a result of the acquisition.

[3] Adjustment consists of mortgage servicing rights assets as a result of the acquisition.(8) Decrease in book value of time deposits to their estimated fair values based upon interest rates of similar time deposits with similar terms on the date of acquisition based upon valuation from an independent accounting and advisory firm. (9) Increase in fair value due to credit card incentive program and swap liability offset.

[4] Adjustment represents the value of the core deposit base assumed in the acquisition based upon valuation from an independent accounting and advisory firm.

[5] Write down of the book value of loans to their estimated fair values. Shared National Credits (SNC) were recorded at quoted sales prices where available. The fair value of the remaining loans was estimated using cash flow projections based on the remaining maturity and repricing terms, adjusted for estimated future credit losses and prepayments and discounted to present value using a risk-adjusted market rate for similar loans. The fair value of collateral dependent loans acquired with deteriorated credit quality was estimated based on the Company's analysis of the fair value of each loan's underlying collateral, discounted using market-derived rates of return with consideration given to the period of time and costs associated with foreclosure and disposition of the collateral.

[6] Adjustment to remove the Cascade allowance for loan losses at acquisition date, as the credit risk is accounted for in the fair value adjustment for loans receivable described in (2) above.

[7] Write up of the book value of premises and equipment to their estimated fair values on the date of acquisition based upon appraisals obtained from an independent third party appraiser or broker's opinion of value.