Capital Stock (Details) - USD ($) $ in Millions		3 Months Ended
	May 30, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Class of Stock [Line Items]
Number of shares issued as partial consideration for acquisition of Cascade Bancorp	11,300,000
Payment amount for repurchase of common stock		$ 0.9	$ 0.9
Class A Common Stock
Class of Stock [Line Items]
Common stock outstanding (in shares)		34,067,912		33,560,202
Stock repurchased and retired (in shares)		0
Class B Common Stock
Class of Stock [Line Items]
Common stock outstanding (in shares)		22,631,503		22,905,357