Acquisitions - Security California Bancorp - Narrative (Details) $ / shares in Units, $ in Thousands	Jan. 31, 2016 USD ($) bank shares	Dec. 31, 2016 USD ($)	Jan. 29, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($)	Jan. 26, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Assets		$ 4,036,311		$ 2,789,599
Total gross loans		3,237,983		2,254,118		$ 1,628,445
Deposits		3,145,485		2,195,123
Closing stock price of common stock (in dollars per share) | $ / shares			$ 20.53
Goodwill		$ 102,490		$ 50,832		$ 22,950
Security California Bancorp
Business Acquisition [Line Items]
Assets	$ 714,000
Total gross loans	456,000
Deposits	$ 637,000
Equity issued (shares)	0.9629
Consideration paid	$ 120,174
Cash consideration	$ 788
Number of branches | bank	6
Goodwill	$ 51,658				$ 51,700
Common Stock | Security California Bancorp
Business Acquisition [Line Items]
Number of shares of common stock issued as consideration | shares	5,815,051
Value of shares of common stock to be issued			$ 119,400