Capital Stock (Details) - USD ($) $ in Thousands		9 Months Ended
	May 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Class of Stock [Line Items]
Number of shares issued as partial consideration for acquisition of Cascade Bancorp	11,300,000
Value of shares issued as partial consideration for acquisition of Cascade Bancorp	$ 385,969
Value of shares issued to board of directors		$ 522
Payment amount for repurchase of common stock		$ 938	$ 26,119
Class A Common Stock
Class of Stock [Line Items]
Common stock outstanding (in shares)		33,383,364		21,613,885
Number of shares issued as partial consideration for acquisition of Cascade Bancorp	11,252,750
Number of shares issued to board of directors		14,926
Stock repurchased and retired (in shares)		0	975,877
Payment amount for repurchase of common stock			$ 25,525
Remaining authorized repurchase amount under stock repurchase program (shares)		24,123
Class B Common Stock
Class of Stock [Line Items]
Common stock outstanding (in shares)		23,072,524		23,312,291