CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2014	$ 2,101.9	$ 146.4	$ (789.5)	$ 364.8	$ 2,414.9	$ (34.7)
Beginning Balance (in shares) at Dec. 31, 2014		146.4	(13.1)
Net Income	107.2	$ 0.0	$ 0.0	0.0	107.2	0.0
Other comprehensive income (loss)	(21.4)	0.0	0.0	0.0	0.0	(21.4)
Cash dividends	(43.7)	0.0	0.0	0.0	(43.7)	0.0
Stock purchases	(256.2)	$ 0.0	$ (256.2)	0.0	0.0	0.0
Stock purchases (in shares)		0.0	(3.1)
Stock based compensation expense and stock option plan transactions, including related income tax benefits	20.9	$ 0.0	$ 20.1	0.8	0.0	0.0
Stock based compensation expense and stock option plan transactions, including related income tax benefits (in shares)		0.0	0.4
Ending Balance at Mar. 31, 2015	1,908.7	$ 146.4	$ (1,025.6)	365.6	2,478.4	(56.1)
Ending Balance (in shares) at Mar. 31, 2015		146.4	(15.8)
Beginning Balance at Dec. 31, 2015	2,023.2	$ 146.4	$ (1,103.7)	376.4	2,650.0	(45.9)
Beginning Balance (in shares) at Dec. 31, 2015		146.4	(16.4)
Net Income	113.0	$ 0.0	$ 0.0	0.0	113.0	0.0
Other comprehensive income (loss)	3.2	0.0	0.0	0.0	0.0	3.2
Cash dividends	(46.1)	0.0	0.0	0.0	(46.1)	0.0
Stock purchases	$ (200.0)	$ 0.0	$ (200.0)	0.0	0.0	0.0
Stock purchases (in shares)	(2.2)	0.0	(2.2)
Stock based compensation expense and stock option plan transactions, including related income tax benefits	$ 27.0	$ 0.0	$ 22.4	4.6	0.0	0.0
Stock based compensation expense and stock option plan transactions, including related income tax benefits (in shares)		0.0	0.3
Ending Balance at Mar. 31, 2016	$ 1,920.3	$ 146.4	$ (1,281.3)	$ 381.0	$ 2,716.9	$ (42.7)
Ending Balance (in shares) at Mar. 31, 2016		146.4	(18.3)