Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Noninterest Income [Abstract]
Total noninterest income in-scope of ASC 606	$ 29,858	$ 27,339
Total noninterest income out-of-scope of ASC 606	1,419	1,411
Total noninterest income	31,277	28,750
Insurance and Other Financial Services Revenue [Member]
Noninterest Income [Abstract]
Total noninterest income in-scope of ASC 606	6,504	6,770
Service Charges on Deposit Accounts [Member]
Noninterest Income [Abstract]
Total noninterest income in-scope of ASC 606	3,972	3,977
ATM and Debit Card Fees [Member]
Noninterest Income [Abstract]
Total noninterest income in-scope of ASC 606	5,273	4,950
Retirement Plan Administration Fees [Member]
Noninterest Income [Abstract]
Total noninterest income in-scope of ASC 606	5,339	4,172
Trust [Member]
Noninterest Income [Abstract]
Total noninterest income in-scope of ASC 606	4,878	4,532
Other [Member]
Noninterest Income [Abstract]
Total noninterest income in-scope of ASC 606	$ 3,892	$ 2,938