Fair Value of Assets & Liabilities - Nonrecurring Fair Value Measurements (Details) - USD ($) $ in Thousands		Mar. 31, 2020		Dec. 31, 2019		Mar. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		$ 13,584		$ 14,033
Loans, net of unearned income		33,378,303	[1]	31,061,111	[1]	$ 27,990,048
OREO	[2]	15,837		17,838
Non Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net of unearned income		31,535		42,208
OREO		13,881		15,660
Other assets		10,262		10,608
Non Recurring | Small Business Administration And USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		494,766		493,524
Non Recurring | First Mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		515		516
Non Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net of unearned income		0		0
OREO		0		0
Other assets		0		0
Non Recurring | Level 1 | Small Business Administration And USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		0		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
Non Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net of unearned income		0		0
OREO		0		0
Other assets		0		0
Non Recurring | Level 2 | Small Business Administration And USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		493,876		492,595
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
Non Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net of unearned income		31,535		42,208
OREO		13,881		15,660
Other assets		10,262		10,608
Non Recurring | Level 3 | Small Business Administration And USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		890		929
Non Recurring | Level 3 | First Mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		$ 515		$ 516

[1] March 31, 2020 and December 31, 2019 include $20.8 million and $18.8 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate in process of foreclosure.

[2] March 31, 2020 and December 31, 2019 include $7.8 million and $9.2 million, respectively, of foreclosed residential real estate.