Capital Stock and Dividend Restrictions (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	May 30, 2017 USD ($) shares	Dec. 31, 2017 USD ($) votes shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)	Sep. 25, 2017 USD ($)	Jan. 26, 2017 shares
Class of Stock
Common stock, shares authorized		200,000,000
Aggregate purchase price of shares repurchased and retired | $		$ 1,348	$ 26,854	$ 20,647
Common stock issued (in shares)	11,300,000
Class A Common Stock
Class of Stock
Common stock, shares authorized		100,000,000
Common stock, voting rights per share (vote per share) | votes		1
Common stock, shares, outstanding		33,560,202	21,613,885
Common shares purchased and retired		0	975,877
Aggregate purchase price of shares repurchased and retired | $			$ 25,500
Weighted average price of shares repurchased and retired (in dollars per share) | $ / shares			$ 26.16
Class B Common Stock
Class of Stock
Common stock, shares authorized		100,000,000
Common stock, voting rights per share (vote per share) | votes		5
Common stock, shares, outstanding		22,905,357	23,312,291
Cascade Bank | Class A Common Stock
Class of Stock
Common stock, shares authorized						11,839,179
Common stock issued (in shares)	11,252,750
Class A common stock | $	$ 386,000
Board of Directors
Class of Stock
Aggregate value of shares issued to directors | $		$ 500	$ 500
Board of Directors | Class A Common Stock
Class of Stock
Shares issued to directors during period		14,926	16,347
Secondary Public Offering | Class A Common Stock
Class of Stock
Common stock, value authorized | $					$ 250,000