CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ (34.1)	$ 508.5	$ 1,041.0	$ 1,386.0
Foreign currency translation adjustments	(4.2)	(36.6)	(11.9)	(32.5)
Pension liability adjustment	0.0	0.0	(7.6)	0.0
Net unrealized gains (losses) related to cash flow hedges:
Unrealized holding gains (losses)	(67.1)	382.8	277.0	342.5
Tax benefit	29.9	0.0	8.3	12.6
Unrealized gains (losses), net of tax expense (benefit) of [$x.x] and ($0.2) for the three months ended September 30, 2014, and 2013, respectively, and [$x.x] and $0 for the nine months ended September 30, 2014, and 2013, respectively.	37.2	(382.8)	(285.3)	(355.1)
Reclassification adjustment for (gains) losses included in net income	(91.4)	(0.1)	(249.6)	4.8
Tax (benefit)	(0.5)	(0.5)	(1.5)	(1.2)
Reclassification adjustment for (gains) losses included in net income, net of tax (expense) benefit of [$x.x] and $0.3 for the three months ended September 30, 2014 and 2013, respectively, and [$x.x] and $6.5 for the nine months ended September 30, 2014 and 2013, respectively.	(91.9)	(0.6)	(251.1)	3.6
Net unrealized gains (losses) on marketable securities available for sale:
Unrealized holding gains (losses)	(426.3)	64.6	(434.6)	196.9
Tax (expense) benefit	133.7	(22.2)	136.8	(67.3)
Unrealized gains (losses), net of tax expense (benefit) of [$x.x] and $58.5 for the three months ended September 30, 2014 and 2013, respectively, and [$x.x] and $78.4 for the nine months ended September 30, 2014 and 2013, respectively.	(292.6)	42.4	(297.8)	129.6
Reclassification adjustment for losses included in net income	10.9	1.2	11.6	4.2
Tax (benefit)	(3.9)	(0.4)	(4.1)	(1.5)
Reclassification adjustment for losses included in net income, net of tax	7.0	0.8	7.5	2.7
Total other comprehensive income (loss)	(418.9)	388.8	(275.6)	458.5
Comprehensive income	$ (453.0)	$ 897.3	$ 765.4	$ 1,844.5