Pension, Savings, And Other Employee Benefits - Narrative (Details) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($) pension_plan	Sep. 30, 2019 USD ($) pension_plan	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Pension plan contribution		$ (509)	$ 0
Defined benefit plan, expected contributions by employer remainder of year	$ 5,200	$ 5,200
Savings Plan
Defined Benefit Plan Disclosure [Line Items]
Employer investment in qualified defined contribution plan		100.00%
Maximum percent of employee pre-tax contributions that may be matched by the Company (percent)		6.00%
Qualified Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Estimated social security benefits age		65 years
Nonqualified Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension plan contribution				$ 5,800
Capital Bank Financial Corp | Qualified Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Number of additional qualified pension plans | pension_plan	2	2
Defined benefit plan, benefit obligation				17,100
Defined benefit plan, fair value of plan assets				$ 16,500
Pension plan contribution	$ 500