Regulatory Capital (Tables)

12 Months Ended

Dec. 31, 2023

Banking Regulation, Risk-Based Information [Abstract]

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations

The Company’s actual capital amounts and ratios and selected minimum regulatory thresholds and prompt corrective action provisions as of December 31, 2023 and 2022 are presented in the following tables:

	Actual				Minimum Required for Capital Adequacy Purposes				For Capital Adequacy Purposes Plus Capital Conservation Buffer(1)				Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements(2)
December 31, 2023	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,941.1	13.28	%	$	1,771.6	8.00	%	$	2,325.2	10.50	%	$	2,214.5	10.00	%
FIB	2,662.0		12.04		1,768.3		8.00		2,320.8		10.50		2,210.3		10.00
Tier 1 risk-based capital:
Consolidated	2,454.4		11.08		1,328.7		6.00		1,882.3		8.50		1,771.6		8.00
FIB	2,433.0		11.01		1,326.2		6.00		1,878.8		8.50		1,768.3		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,454.4		11.08		996.5		4.50		1,550.1		7.00		1,439.4		6.50
FIB	2,433.0		11.01		994.6		4.50		1,547.2		7.00		1,436.7		6.50
Leverage capital ratio:
Consolidated	2,454.4		8.22		1,193.9		4.00		1,193.9		4.00		1,492.3		5.00
FIB	2,433.0		8.16		1,192.2		4.00		1,192.2		4.00		1,490.2		5.00

December 31, 2022	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,875.8	12.48	%	$	1,843.2	8.00	%	$	2,419.2	10.50	%	$	2,304.0	10.00	%
FIB	2,713.5		11.80		1,839.6		8.00		2,414.5		10.50		2,299.5		10.00
Tier 1 risk-based capital:
Consolidated	2,408.8		10.45		1,382.4		6.00		1,958.4		8.50		1,843.2		8.00
FIB	2,504.1		10.89		1,379.7		6.00		1,954.6		8.50		1,839.6		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,408.8		10.45		1,036.8		4.50		1,612.8		7.00		1,497.6		6.50
FIB	2,504.1		10.89		1,034.8		4.50		1,609.7		7.00		1,494.7		6.50
Leverage capital ratio:
Consolidated	2,408.8		7.75		1,242.9		4.00		1,242.9		4.00		1,553.6		5.00
FIB	2,504.1		8.07		1,241.1		4.00		1,241.1		4.00		1,551.4		5.00

(1) The capital conservation buffer is an additional 2.5% of the amount necessary to meet the minimum risk-based capital requirements for total, tier 1, and common equity tier 1 risk-based capital.

(2) The ratios to meet the requirements to be deemed “well-capitalized” are only applicable to FIB. However, the Company manages its capital position as if the requirements apply to the consolidated company and has presented the ratios as if they also applied on a consolidated basis