Capital Stock and Dividend Restrictions (Details) - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended	12 Months Ended
	Jul. 31, 2014	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Apr. 03, 2015	Jan. 24, 2014
Preferred Stock
Nonvoting, noncumulative preferred stock, shares outstanding			0	0
Common Stock, Recapitalization
Common stock, shares authorized			200,000,000
Common Stock
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned			$ 35,972
Payments for Repurchase of Common Stock			$ 20,647	$ 9,739	$ 448
Class B Common Stock
Common Stock, Recapitalization
Common stock, shares authorized			100,000,000
Common Stock, Voting Rights			5
Common Stock
Common stock, shares, outstanding			23,729,631	23,859,483
Class A Common Stock
Class of Stock
Stock Repurchased and Retired During Period, Weighted Average Price			$ 26.01
Common Stock, Recapitalization
Common stock, shares authorized			100,000,000
Common Stock, Voting Rights			1
Common Stock
Common stock, shares, outstanding			21,698,594	21,928,932
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 35,972
Stock Repurchased and Retired During Period, Shares			765,875
Payments for Repurchase of Common Stock			$ 19,921
2015 Equity Compensation Plan [Member] | Class A Common Stock
Class of Stock
Additional Shares Authorized						2,000,000
Amendment to 2006 Equity Compensation Plan [Domain] | Class A Common Stock
Class of Stock
Additional Shares Authorized							1,500,000
Mountain West Bank | Class A Common Stock
Common Stock
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	1,378,230		1,378,230
Board of Directors [Member]
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award, Aggregate Value of Shares Issued		$ 591		$ 620
Board of Directors [Member] | Class A Common Stock
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period		21,414		24,581