Condensed Consolidated Statements of Changes in Shareholders' Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Deficit), Appropriated	Retained Earnings (Deficit), Unappropriated	Shareholders' Equity	Noncontrolling Interest
Ending balance at Dec. 31, 2011	$ 13,926.1	$ 2.3	$ 22,865.2	$ 2,595.0	$ 126.5	$ (13,235.1)	$ 12,353.9	$ 1,572.2
Comprehensive income:
Net income (loss)	718.1					495.7	495.7	222.4
Other comprehensive income (loss), after tax	1,106.5			1,106.5			1,106.5
Total comprehensive income (loss)	1,824.6						1,602.2	222.4
Reclassification of noncontrolling interest	0				(78.1)		(78.1)	78.1
Common Stock Issuance	0	0	0				0
Dividends on common stock	0		0				0
Employee related benefits	32.5		32.5				32.5
Contribution from (Distribution to) noncontrolling interest, net	168.3							168.3
Beginning balance at Sep. 30, 2012	15,951.5	2.3	22,897.7	3,701.5	48.4	(12,739.4)	13,910.5	2,041.0
Ending balance at Dec. 31, 2012	16,061.2	2.3	22,917.6	3,710.7	6.4	(12,762.1)	13,874.9	2,186.3
Comprehensive income:
Net income (loss)	136.9					52.4	52.4	84.5
Other comprehensive income (loss), after tax	(1,760.7)			(1,760.7)			(1,760.7)
Total comprehensive income (loss)	(1,623.8)						(1,708.3)	84.5
Reclassification of noncontrolling interest	0				(4.0)		(4.0)	4.0
Common Stock Issuance	571.6	0.3	571.3				571.6
Dividends on common stock	(2.6)		(2.6)				(2.6)
Employee related benefits	38.4		38.4				38.4
Contribution from (Distribution to) noncontrolling interest, net	(180.3)							(180.3)
Beginning balance at Sep. 30, 2013	$ 14,864.5	$ 2.6	$ 23,524.7	$ 1,950.0	$ 2.4	$ (12,709.7)	$ 12,770.0	$ 2,094.5