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

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Securities Purchased under Agreements to Resell

($ In Millions)	2017			2016
Balance at December 31	$	1,303.3		$	1,967.5
Average Balance During the Year	1,832.0			1,764.1
Average Interest Rate Earned During the Year	1.48		%	1.04		%
Maximum Month-End Balance During the Year	2,064.1			2,050.9

Securities Sold under Agreements to Repurchase

($ In Millions)	2017			2016
Balance at December 31	$	834.0		$	473.7
Average Balance During the Year	738.9			847.1
Average Interest Rate Paid During the Year	0.81		%	0.27		%
Maximum Month-End Balance During the Year	834.0			565.5