Other Noninterest Income and Other Noninterest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Operating Cost and Expense [Line Items]
Other Noninterest Income	$ 47,841	$ 34,170	$ 36,359
Other Noninterest Expense	186,199	180,715	172,440
Gain On Termination of Forward Starting Advance	12,500
PCI Loans
Other Operating Cost and Expense [Line Items]
Proceeds from Recoveries of Loans Previously Charged off	21,100	20,100	21,200
Processing Fees Paid To Third Parties
Other Operating Cost and Expense [Line Items]
Other Noninterest Expense	25,673	18,976	18,779
Cardholder Reward Programs
Other Operating Cost and Expense [Line Items]
Other Noninterest Expense	9,956	10,615	11,069
Telecommunication
Other Operating Cost and Expense [Line Items]
Other Noninterest Expense	12,172	14,496	14,406
Consultant
Other Operating Cost and Expense [Line Items]
Other Noninterest Expense	14,963	10,931	8,925
Core Deposit Intangible Amortization
Other Operating Cost and Expense [Line Items]
Other Noninterest Expense	17,194	16,851	18,892
Advertising
Other Operating Cost and Expense [Line Items]
Other Noninterest Expense	11,227	10,239	12,431
Other Expense
Other Operating Cost and Expense [Line Items]
Other Noninterest Expense	$ 95,014	$ 98,607	$ 87,938