Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning balance	$ 268,043	$ 265,439
Goodwill acquired	6,726	2,604
Ending balance	274,769	268,043	$ 265,439
Finite-Lived Intangible Assets [Abstract]
Gross carrying amount	43,598	42,607
Less: accumulated amortization	27,999	29,187
Net carrying amount	15,599	13,420
Impairment of goodwill	0	0
Amortization Expense [Abstract]
Amortization of intangible assets	4,042	3,960	$ 3,928
Future Amortization Expense [Abstract]
2019	3,600
2020	3,000
2021	2,300
2022	1,800
2023	1,400
Thereafter	3,500
Impairment of intangible assets	$ 0	1,500
Minimum [Member]
Finite-Lived Intangible Assets [Abstract]
Intangible asset useful life	1 year
Maximum [Member]
Finite-Lived Intangible Assets [Abstract]
Intangible asset useful life	20 years
Core Deposits Intangibles [Member]
Finite-Lived Intangible Assets [Abstract]
Gross carrying amount	$ 8,975	8,975
Less: accumulated amortization	7,377	6,581
Net carrying amount	1,598	2,394
Identified Intangible Assets [Member]
Finite-Lived Intangible Assets [Abstract]
Gross carrying amount	34,623	33,632
Less: accumulated amortization	20,622	22,606
Net carrying amount	$ 14,001	$ 11,026