Unaudited Consolidated Statement of Stockholders' Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive (Loss), Net of Tax	Noncontrolling Interests
Balance at Dec. 31, 2012	$ 7,705.7	$ 4.1	$ 6,588.9	$ 2,403.2	$ (1,287.1)	$ (5.8)	$ 2.4
Balance (in shares) at Dec. 31, 2012		405.2			(44.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	181.3	0	0	180.9	0	0	0.4
Other comprehensive income	(1.6)	0	0	0	0	(1.6)	0
Cash dividends declared	(170.0)	0	0	(170.0)	0	0	0
Issuances of common stock		0	125.0	0	0	0	0
Issuances of common stock (in shares)		4.9			0
Stock-based compensation		0	9.5	(1.1)	0	0	0
Purchase of common stock for treasury		0	0	0	(135.6)	0	0
Purchase of common stock for treasury (in shares)		0			(4.1)
Balance at Jun. 30, 2013	$ 7,713.2	$ 4.1	$ 6,723.4	$ 2,413.0	$ (1,422.7)	$ (7.4)	$ 2.8
Balance (in shares) at Jun. 30, 2013		410.1			(48.2)