Organization and Summary of Significant Accounting Policies - Accounting Standards Adopted and Recent Accounting Pronouncements (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Corporate tax rate (as a percent)		21.00%	35.00%	35.00%
ASU 2016-02 | Restatement adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset on consolidated balance sheet					$ 50.0
Recognized lease liability on consolidated balance sheet					$ 50.0
ASU 2018-02 | Early adoption effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassified credit balance from AOCL to retained earnings	$ 20.1
ASU 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Salaries and employee benefits reclassified to other noninterest expense			$ 12.3	$ 12.1