CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Common Stock and Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Non-controlling Interests	Total
Balance at Dec. 31, 2015	$ 533.8	$ 3,480.0	$ (99.7)	$ 28.6	$ 3,942.7
Balance (in shares) at Dec. 31, 2015	71,739,000
Increase (Decrease) in Stockholders' Equity
Net income		304.3		4.8	309.1
Other comprehensive income (loss)			(5.0)		(5.0)
Payments to noncontrolling interest holders				(3.1)	(3.1)
Stock-based compensation, net	$ 18.0				18.0
Stock-based compensation, net (in shares)	189,000
Stock options exercised	$ 37.5				37.5
Stock options exercised (in shares)	755,000
Cumulative effect of change in accounting for stock-based compensation	$ 1.0	(0.6)			$ 0.4
Repurchase of common shares (in shares)					0
Cash dividends - $2.00 and $1.80 and $1.65 and per share for the year ended on December 31, 2018 and December 31, 2017 and December 31, 2016, respectively		(120.5)			$ (120.5)
Balance at Dec. 31, 2016	$ 590.3	3,663.2	(104.7)	30.3	4,179.1
Balance (in shares) at Dec. 31, 2016	72,683,000
Increase (Decrease) in Stockholders' Equity
Net income		613.4		7.6	621.0
Other comprehensive income (loss)			33.1		33.1
Payments to noncontrolling interest holders				(5.1)	(5.1)
Stock-based compensation, net	$ 24.1				24.1
Stock-based compensation, net (in shares)	165,000
Stock options exercised	$ 5.2				5.2
Stock options exercised (in shares)	99,000
Repurchase of common shares	$ (25.0)				$ (25.0)
Repurchase of common shares (in shares)	(337,000)				300,000
Cash dividends - $2.00 and $1.80 and $1.65 and per share for the year ended on December 31, 2018 and December 31, 2017 and December 31, 2016, respectively		(132.5)			$ (132.5)
Balance at Dec. 31, 2017	$ 594.6	4,144.1	(71.6)	32.8	$ 4,699.9
Balance (in shares) at Dec. 31, 2017	72,610,000				72,610,000
Increase (Decrease) in Stockholders' Equity
Net income		633.7		8.1	$ 641.8
Other comprehensive income (loss)			(25.6)		(25.6)
Reclassification of stranded tax effects resulting from tax reform		5.5	(5.5)
Noncontrolling interest purchased	$ (9.3)			(19.7)	(29.0)
Payments to noncontrolling interest holders				(13.3)	(13.3)
Stock-based compensation, net	$ 33.2				33.2
Stock-based compensation, net (in shares)	289,000
Stock options exercised	$ 2.8				2.8
Stock options exercised (in shares)	48,000
Repurchase of common shares	$ (484.9)				$ (484.9)
Repurchase of common shares (in shares)	(6,065,000)				6,100,000
Cash dividends - $2.00 and $1.80 and $1.65 and per share for the year ended on December 31, 2018 and December 31, 2017 and December 31, 2016, respectively		(145.4)			$ (145.4)
Balance at Dec. 31, 2018	$ 136.4	$ 4,637.9	$ (102.7)	$ 7.9	$ 4,679.5
Balance (in shares) at Dec. 31, 2018	66,882,000				66,882,000