Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Assets, Fair Value Disclosure [Abstract]
Other Investments		$ 38,200	$ 26,400
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Valuation allowance of impaired loans		3,300	4,000
Other Liabilities
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, beginning of period		0	0
Total realized gains included in income		0	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)			0
Purchases		0	0
Issuances		0	0
Settlements		0	0
Transfers out of Level 3		0	0
Fair value, December 31		0	0
Other Assets
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, beginning of period		26,422	28,874
Total realized gains included in income		2,785	2,932
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0	0
Purchases		11,297	9,013
Issuances		0	0
Settlements		(2,348)	(2,231)
Transfers out of Level 3		0	(12,166)
Fair value, December 31		38,156	26,422
Available-for-sale Securities
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, beginning of period		14,595	17,029
Total realized gains included in income		116	(34)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		2,710	(1,232)
Purchases		0	0
Issuances		0	0
Settlements		(1,518)	(1,168)
Transfers out of Level 3		0	0
Fair value, December 31		15,903	14,595
Fair Value, Measurements, Nonrecurring
Assets, Fair Value Disclosure [Abstract]
Total assets at fair value		61,964	55,995
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned		29,487	15,165
Impaired Financing Receivable, with Related Allowance, Recorded Investment	[1]	32,477	40,830
Gain loss on Other real estate owned		(2,927)	(84)
Total losses on collateral dependent nonaccrual loans, net	[1]	(656)	(1,214)
Total losses		(3,583)	(1,298)
Fair Value, Measurements, Nonrecurring | Quoted Market Prices in an Active Market (Level 1)
Assets, Fair Value Disclosure [Abstract]
Total assets at fair value		0	0
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned		0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	[1]	0	0
Fair Value, Measurements, Nonrecurring | Models with Significant Observable Market Parameters (Level 2)
Assets, Fair Value Disclosure [Abstract]
Total assets at fair value		0	0
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned		0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	[1]	0	0
Fair Value, Measurements, Nonrecurring | Models with Significant Unobservable Market Parameters (Level 3)
Assets, Fair Value Disclosure [Abstract]
Total assets at fair value		61,964	55,995
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned		29,487	15,165
Impaired Financing Receivable, with Related Allowance, Recorded Investment	[1]	32,477	40,830
Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
U.S. treasury securities		72,867	30,300
U.S. government agency securities		79,692	70,159
Mortgage-backed securities		1,463,907	1,310,945
State and municipal securities		1,714,453	1,229,654
Asset-backed securities		152,972	375,582
Corporate notes and other		56,104	67,046
Total investment securities available-for-sale		3,539,995	3,083,686
Other Investments		63,291	50,791
Other assets		134,040	24,524
Total assets at fair value		3,737,326	3,159,001
Liabilities at fair value [Abstract]
Other liabilities		87,613	46,550
Total liabilities at fair value		87,613	46,550
Fair Value, Measurements, Recurring | Quoted Market Prices in an Active Market (Level 1)
Assets, Fair Value Disclosure [Abstract]
U.S. treasury securities		0	0
U.S. government agency securities		0	0
Mortgage-backed securities		0	0
State and municipal securities		0	0
Asset-backed securities		0	0
Corporate notes and other		0	0
Total investment securities available-for-sale		0	0
Other Investments		0	0
Other assets		0	0
Total assets at fair value		0	0
Liabilities at fair value [Abstract]
Other liabilities		0	0
Total liabilities at fair value		0	0
Fair Value, Measurements, Recurring | Models with Significant Observable Market Parameters (Level 2)
Assets, Fair Value Disclosure [Abstract]
U.S. treasury securities		72,867	30,300
U.S. government agency securities		79,692	70,159
Mortgage-backed securities		1,463,907	1,310,945
State and municipal securities		1,698,550	1,215,059
Asset-backed securities		152,972	375,582
Corporate notes and other		56,104	67,046
Total investment securities available-for-sale		3,524,092	3,069,091
Other Investments		25,135	24,369
Other assets		134,040	24,524
Total assets at fair value		3,683,267	3,117,984
Liabilities at fair value [Abstract]
Other liabilities		87,613	46,550
Total liabilities at fair value		87,613	46,550
Fair Value, Measurements, Recurring | Models with Significant Unobservable Market Parameters (Level 3)
Assets, Fair Value Disclosure [Abstract]
U.S. treasury securities		0	0
U.S. government agency securities		0	0
Mortgage-backed securities		0	0
State and municipal securities		15,903	14,595
Asset-backed securities		0	0
Corporate notes and other		0	0
Total investment securities available-for-sale		15,903	14,595
Other Investments		38,156	26,422
Other assets		0	0
Total assets at fair value		54,059	41,017
Liabilities at fair value [Abstract]
Other liabilities		0	0
Total liabilities at fair value		$ 0	$ 0

[1] Amount is net of a valuation allowance of $3.3 million and $4.0 million at December 31, 2019 and 2018, respectively, as required by ASC 310-10, "Receivables."