Business Combination (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended	0 Months Ended	3 Months Ended	9 Months Ended		0 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Mountain West Bank	Jul. 31, 2014 Mountain West Bank	Sep. 30, 2014 Mountain West Bank	Sep. 30, 2014 Mountain West Bank	Feb. 10, 2014 Mountain West Bank	Jul. 31, 2014 Mountain West Bank Class A Common Stock	Sep. 30, 2014 Mountain West Bank Class A Common Stock	Jul. 31, 2014 Mountain West Bank Class A Common Stock	Feb. 10, 2014 Mountain West Bank Class A Common Stock
Business Acquisition [Line Items]
Number of Subsidiary Banks					1
Number of Shared Markets					5
Business Acquisition, Effective Date of Acquisition						Jul. 31, 2014
Business Acquisition Conversion Share Rate													0.2552
Business Acquisition Conversion Rate									$ 7.125
Payments to Acquire Businesses, Gross						$ 38,479
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares										1,378,230	1,378,230
Business Combination, Consideration Transferred						74,451
Business Acquisition, Share Price												$ 26.10
Business Combination, Acquisition Related Costs	$ 5,052	$ 0	$ 5,649	$ 0			$ 1,053	$ 1,649