Acquisitions Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jul. 24, 2015	Jul. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned			$ 35,972
Goodwill			$ 204,523	$ 205,574
Class A Common Stock
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned		$ 35,972
United Bank Acquisition, as recorded by Company [Member]
Business Acquisition [Line Items]
Cash and Cash Equivalents	$ 5,598
Investment Securities	27,574
Loans	36,644
Allowance for Loan Losses	0
Premises and Equipment	3,128
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Company Owned LIfe Insurance	0
Core Deposit Intangibles	695
Other Assets	898
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	74,537
Deposits	63,565
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Securities Under Agreement to Repurchase	2,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	1,253
Other Liabilities	633
Subordinated Debentures Held by Subsidiary Trusts	0
Total Liabilities Assumed	67,451
Net Assets Acquired	7,086
Payments to Acquire Businesses, Gross	7,234
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	0
Business Combination, Consideration Transferred	7,234
Goodwill	$ 148
Mountain West Bank Acquisition, As Recorded by the Company
Business Acquisition [Line Items]
Cash and Cash Equivalents		74,035
Investment Securities		104,911
Loans		360,272
Allowance for Loan Losses		0
Premises and Equipment		29,436
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Company Owned LIfe Insurance		13,046
Core Deposit Intangibles		11,014
Other Assets		18,885
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		611,599
Deposits		515,379
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Securities Under Agreement to Repurchase		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt		0
Other Liabilities		23,231
Subordinated Debentures Held by Subsidiary Trusts		20,439
Total Liabilities Assumed		559,049
Net Assets Acquired		52,550
Payments to Acquire Businesses, Gross		38,479
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned		35,972
Business Combination, Consideration Transferred		74,451
Goodwill		$ 21,901