Consolidated Statement of Changes in Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net change in unrealized gains on available-for-sale securities, net tax benefit	$ 0.0	$ (0.2)	$ (0.1)	$ (1.0)
Net unrealized gains on cash flow hedges, net tax provision	(30.1)	(104.2)	49.8	1.9
Postretirement plans and workers' compensation obligations, net tax provision	$ 1.8	$ 4.0	$ 11.2	$ 1.8