CONSOLIDATED STATEMENTS OF EQUITY (USD $) In Millions, except Share data, unless otherwise specified	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interests	Total
Balance at Dec. 31, 2011	$ 657.1	$ 2,495.6	$ (8.8)	$ 8.1	$ 3,152.0
Balance (in shares) at Dec. 31, 2011	75,007,694
Increase (Decrease) in Stockholders' Equity
Net income		403.5		4.8	408.3
Other comprehensive income			7.3		7.3
Noncontrolling interests purchased				(0.8)	(0.8)
Payments to noncontrolling interest holders				(3.1)	(3.1)
Share-based compensation	23.0				23.0
Share-based compensation (in shares)	16,842
Stock options exercised	42.1				42.1
Stock options exercised (in shares)	1,018,010
Share-based compensation tax benefit (deficit)		(1.2)			(1.2)
Cash dividends - $1.40, $1.26 and $0.80 per share for the year ended on December 31, 2014, December 31, 2013 and December 31, 2012, respectively		(60.2)			(60.2)
Balance at Dec. 31, 2012	722.2	2,837.7	(1.5)	9.0	3,567.4
Balance (in shares) at Dec. 31, 2012	76,042,546
Increase (Decrease) in Stockholders' Equity
Net income		321.6		3.1	324.7
Other comprehensive income			(5.2)		(5.2)
Payments to noncontrolling interest holders				(2.3)	(2.3)
Share-based compensation	26.0				26.0
Share-based compensation (in shares)	12,418
Stock options exercised	70.1				70.1
Stock options exercised (in shares)	1,437,053
Share-based compensation tax benefit (deficit)		0.6			0.6
Cash dividends - $1.40, $1.26 and $0.80 per share for the year ended on December 31, 2014, December 31, 2013 and December 31, 2012, respectively		(96.9)			(96.9)
Balance at Dec. 31, 2013	818.3	3,063.0	(6.7)	9.8	3,884.4
Balance (in shares) at Dec. 31, 2013	77,492,017				77,492,017
Increase (Decrease) in Stockholders' Equity
Net income		371.5		4.8	376.3
Other comprehensive income			(42.2)		(42.2)
Consolidation of joint venture				22.6	22.6
Noncontrolling interests purchased				(4.2)	(4.2)
Payments to noncontrolling interest holders				(4.1)	(4.1)
Share-based compensation	22.3				22.3
Share-based compensation (in shares)	11,830
Stock options exercised	28.8				28.8
Stock options exercised (in shares)	593,204
Repurchase of common shares	(50.0)				(50.0)
Repurchase of common shares (in shares)	(759,800)
Share-based compensation tax benefit (deficit)		2.7			2.7
Cash dividends - $1.40, $1.26 and $0.80 per share for the year ended on December 31, 2014, December 31, 2013 and December 31, 2012, respectively		(108.7)			(108.7)
Balance at Dec. 31, 2014	$ 819.4	$ 3,328.5	$ (48.9)	$ 28.9	$ 4,127.9
Balance (in shares) at Dec. 31, 2014	77,337,251				77,337,251