Fair Value of Financial Instruments - Changes in Fair Value Associated with Commercial Loans Held for Sale (Details) - Franklin Financial Network, Inc. - Commercial and industrial - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Aggregate Unpaid Principal Balance
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Carrying value at beginning of period	$ 47,462	$ 135,972	$ 86,762	$ 239,063
Change in fair value:
Pay-downs and pay-offs	(3,706)	(24,366)	(43,006)	(116,158)
Write-offs to discount	(8,729)		(8,729)	(11,299)
Changes in valuation included in other noninterest income	0	0	0	0
Carrying value at end of period	35,027	111,606	35,027	111,606
Fair Value Discount
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Carrying value at beginning of period	(9,647)	(11,850)	(7,463)	(23,660)
Change in fair value:
Pay-downs and pay-offs	0	0		0
Write-offs to discount	8,729		8,729	11,299
Changes in valuation included in other noninterest income	(387)	740	(2,571)	1,251
Carrying value at end of period	(1,305)	(11,110)	(1,305)	(11,110)
Fair Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Carrying value at beginning of period	37,815	124,122	79,299	215,403
Change in fair value:
Pay-downs and pay-offs	(3,706)	(24,366)	(43,006)	(116,158)
Write-offs to discount	0		0	0
Changes in valuation included in other noninterest income	(387)	740	(2,571)	1,251
Carrying value at end of period	$ 33,722	$ 100,496	$ 33,722	$ 100,496