Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net change in unrealized holding losses on available-for-sale securities, tax benefit	$ 0.3	$ 3.7	$ (0.8)	$ (0.1)
Net unrealized gains on cash flow hedges, tax provision	37.2	(217.1)	106.1	(228.0)
Postretirement plans and workers' compensation obligations, tax benefit	$ 4.0	$ 8.4	$ (2.2)	$ 16.7