CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Common Stock Including Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interests	Total
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 (loss)			(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
Stock-based compensation tax benefit (deficit)		0.6			0.6
Cash dividends - $1.40 and $1.26 per share for the year ended on December 31, 2014 and December 31, 2013, 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
Increase (Decrease) in Stockholders' Equity
Net income		371.5		4.8	376.3
Other comprehensive income (loss)			(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)				(759,800)
Stock-based compensation tax benefit (deficit)		2.7			$ 2.7
Cash dividends - $1.40 and $1.26 per share for the year ended on December 31, 2014 and December 31, 2013, 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
Increase (Decrease) in Stockholders' Equity
Net income		311.5		4.7	$ 316.2
Other comprehensive income (loss)			(50.8)		(50.8)
Noncontrolling interests purchased	$ (0.6)			(2.0)	(2.6)
Payments to noncontrolling interest holders				(3.0)	(3.0)
Share-based compensation	$ 16.8				16.8
Share-based compensation (in shares)	271,438
Stock options exercised	$ 15.1				15.1
Stock options exercised (in shares)	325,024
Repurchase of common shares	$ (355.5)				$ (355.5)
Repurchase of common shares (in shares)	(6,194,641)				(6,194,641)
Stock-based compensation tax benefit (deficit)		(1.3)			$ (1.3)
Delaware reincorporation	$ 38.6	(38.6)
Cash dividends and dividend equivalents - $1.60 per share for the year ended on December 31, 2015		(120.1)			(120.1)
Balance at Dec. 31, 2015	$ 533.8	$ 3,480.0	$ (99.7)	$ 28.6	$ 3,942.7
Balance (in shares) at Dec. 31, 2015	71,739,072				71,739,072