Organization and Summary of Significant Accounting Policies - Correction of Immaterial Errors (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Correction of an Immaterial Error to the Financial Statements
Service charges on deposit accounts	$ 35,807	$ 37,392	$ 40,058
Credit and debit card fee income	64,049	65,262	64,916
Occupancy expense	23,485	21,606	18,401
Card rewards program expense	23,363	22,459	23,969
Net income	$ 183,682	230,178	213,780
Restatement adjustment | Misclassifications of noninterest income and noninterest expense
Correction of an Immaterial Error to the Financial Statements
Service charges on deposit accounts		(800)	(800)
Credit and debit card fee income		9,200	8,500
Occupancy expense		1,500	1,400
Card rewards program expense		6,900	6,300
Net income		$ 0	$ 0
Earnings per share (basic and diluted) (in dollars per share)		$ 0.00	$ 0.00