Fair Value of Assets and Liabilities - Nonrecurring Fair Value Measurements (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		$ 14,033		$ 16,273
Loans, net of unearned income		31,061,111	[1]	27,535,532	[1]	$ 27,658,929
Other real estate owned (OREO)	[2]	17,838		25,290
Non Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net of unearned income		42,208		48,259		26,666
Other real estate owned (OREO)		15,660		22,387		39,566
Other assets		10,608		8,845		26,521
Net gains (losses) loans, net of unearned income		(7,341)		(841)		(1,687)
Net gains (losses) other real estate owned		(927)		(2,599)		(996)
Net gains (losses) other assets		(1,809)		(4,712)		(3,468)
Net gains (losses) financial assets		(11,862)		(12,489)		(7,744)
Non Recurring | SBAs and USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		493,524		578,291		466,977
Net gains (losses) loans held-for-sale		(1,817)		(2,541)		(1,629)
Non Recurring | Other Consumer Loans Class
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale				18,712
Net gains (losses) loans held-for-sale				(1,809)
Non Recurring | First Mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		516		541		618
Net gains (losses) loans held-for-sale		32		13		36
Non Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net of unearned income		0		0		0
Other real estate owned (OREO)		0		0		0
Other assets		0		0		0
Non Recurring | Level 1 | SBAs and USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		0		0		0
Non Recurring | Level 1 | Other Consumer Loans Class
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale				0
Non Recurring | Level 1 | First Mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		0		0		0
Non Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net of unearned income		0		0		0
Other real estate owned (OREO)		0		0		0
Other assets		0		0		0
Non Recurring | Level 2 | SBAs and USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		492,595		577,280		465,504
Non Recurring | Level 2 | Other Consumer Loans Class
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale				18,712
Non Recurring | Level 2 | First Mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		0		0		0
Non Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net of unearned income		42,208		48,259		26,666
Other real estate owned (OREO)		15,660		22,387		39,566
Other assets		10,608		8,845		26,521
Non Recurring | Level 3 | SBAs and USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		929		1,011		1,473
Non Recurring | Level 3 | Other Consumer Loans Class
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale				0
Non Recurring | Level 3 | First Mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		$ 516		$ 541		$ 618

[1] December 31, 2019 and 2018 include $18.8 million and $28.6 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate in process of foreclosure.

[2] December 31, 2019 and 2018 include $9.2 million and $9.7 million, respectively, of foreclosed residential real estate.