Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase (Tables)

12 Months Ended

Dec. 31, 2021

Investments, Debt and Equity Securities [Abstract]

Securities Purchased under Agreements to Resell

($ In Millions)	2021			2020
Balance at December 31	$	686.4		$	1,596.5
Average Balance During the Year	1,067.4			1,253.1
Average Interest Rate Earned During the Year	0.33		%	0.31		%
Maximum Month-End Balance During the Year	$	1,819.1		$	2,055.6

Securities Sold under Agreements to Repurchase

($ In Millions)	2021			2020
Balance at December 31	$	531.9		$	39.8
Average Balance During the Year	232.0			218.3
Average Interest Rate Paid During the Year	0.07		%	0.47		%
Maximum Month-End Balance During the Year	$	892.6		$	269.8

Transfer of Certain Financial Assets Accounted for as Secured Borrowings

	REMAINING CONTRACTUAL MATURITY OF THE AGREEMENTS
	December 31, 2021						December 31, 2020
($ In Millions)	OVERNIGHT AND CONTINUOUS		UP TO 30 DAYS		TOTAL		OVERNIGHT AND CONTINUOUS		UP TO 30 DAYS		TOTAL
U.S. Treasury and Agency Securities	$	32.4	$	499.5	$	531.9	$	39.8	$	—	$	39.8
Total Borrowings	32.4		499.5		531.9		39.8		—		39.8
Net Amount of Recognized Liabilities for Repurchase Agreements in Note 28	32.4		499.5		531.9		39.8		—		39.8
Amounts related to agreements not included in Note 28	—		—		—		—		—		—