Organization and Summary of Significant Accounting Policies - Correction of Immaterial Error (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Correction of an Immaterial Error to the Financial Statements
Service charges on deposit accounts	$ (7,721)	$ (9,238)	$ (15,676)	$ (18,619)
Credit and debit card fees	16,929	16,019	32,426	32,324
Occupancy expense	6,908	5,435	13,392	11,144
Card rewards program expense	6,359	5,894	12,077	11,669
Net income	$ 69,053	56,895	$ 137,011	113,635
Restatement adjustment | Misclassifications of noninterest income and noninterest expense
Correction of an Immaterial Error to the Financial Statements
Service charges on deposit accounts		200		400
Credit and debit card fees		1,900		3,700
Occupancy expense		400		800
Card rewards program expense		$ 1,300		2,500
Net income				$ 0