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, 2018	$ 2,453.8	$ 292.8	$ (1,898.8)	$ 280.8	$ 3,832.6	$ (53.6)
Beginning Balance (in shares) at Dec. 31, 2018		292.8	(46.0)
Adoption of new accounting pronouncements	13.0	$ 0.0	$ 0.0	0.0	13.0	0.0
Net Income	175.7	0.0	0.0	0.0	175.7	0.0
Other comprehensive income (loss)	(5.9)	0.0	0.0	0.0	0.0	(5.9)
Cash dividends	(55.9)	(0.0)	(0.0)	(0.0)	(55.9)	(0.0)
Stock purchases	(100.0)	$ (0.0)	$ (100.0)	(0.0)	(0.0)	(0.0)
Stock purchases (in shares)		(0.0)	(1.5)
Stock based compensation expense and stock option plan transactions	18.6	$ 0.0	$ 18.1	0.5	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	0.7
Ending Balance at Mar. 31, 2019	2,499.3	$ 292.8	$ (1,980.7)	281.3	3,965.4	(59.5)
Ending Balance (in shares) at Mar. 31, 2019		292.8	(46.8)
Beginning Balance at Dec. 31, 2018	2,453.8	$ 292.8	$ (1,898.8)	280.8	3,832.6	(53.6)
Beginning Balance (in shares) at Dec. 31, 2018		292.8	(46.0)
Net Income	314.2
Other comprehensive income (loss)	(14.8)
Ending Balance at Jun. 30, 2019	2,604.8	$ 292.8	$ (1,955.7)	288.3	4,047.8	(68.4)
Ending Balance (in shares) at Jun. 30, 2019		292.8	(45.9)
Beginning Balance at Mar. 31, 2019	2,499.3	$ 292.8	$ (1,980.7)	281.3	3,965.4	(59.5)
Beginning Balance (in shares) at Mar. 31, 2019		292.8	(46.8)
Net Income	138.5	$ 0.0	$ 0.0	0.0	138.5	0.0
Other comprehensive income (loss)	(8.9)	0.0	0.0	0.0	0.0	(8.9)
Cash dividends	(56.1)	(0.0)	(0.0)	(0.0)	(56.1)	(0.0)
Stock based compensation expense and stock option plan transactions	32.0	$ 0.0	$ 25.0	7.0	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	0.9
Ending Balance at Jun. 30, 2019	2,604.8	$ 292.8	$ (1,955.7)	288.3	4,047.8	(68.4)
Ending Balance (in shares) at Jun. 30, 2019		292.8	(45.9)
Beginning Balance at Dec. 31, 2019	2,667.8	$ 292.8	$ (2,091.2)	295.5	4,237.4	(66.7)
Beginning Balance (in shares) at Dec. 31, 2019		292.8	(47.4)
Net Income	229.8	$ 0.0	$ 0.0	0.0	229.8	0.0
Other comprehensive income (loss)	(32.7)	0.0	0.0	0.0	0.0	(32.7)
Cash dividends	(59.0)	(0.0)	(0.0)	(0.0)	(59.0)	(0.0)
Stock based compensation expense and stock option plan transactions	11.9	$ 0.0	$ 11.7	0.2	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	0.3
Ending Balance at Mar. 31, 2020	2,817.8	$ 292.8	$ (2,079.5)	295.7	4,408.2	(99.4)
Ending Balance (in shares) at Mar. 31, 2020		292.8	(47.1)
Beginning Balance at Dec. 31, 2019	2,667.8	$ 292.8	$ (2,091.2)	295.5	4,237.4	(66.7)
Beginning Balance (in shares) at Dec. 31, 2019		292.8	(47.4)
Net Income	419.5
Other comprehensive income (loss)	(31.6)
Ending Balance at Jun. 30, 2020	2,998.8	$ 292.8	$ (2,037.3)	302.8	4,538.8	(98.3)
Ending Balance (in shares) at Jun. 30, 2020		292.8	(45.9)
Beginning Balance at Mar. 31, 2020	2,817.8	$ 292.8	$ (2,079.5)	295.7	4,408.2	(99.4)
Beginning Balance (in shares) at Mar. 31, 2020		292.8	(47.1)
Net Income	189.7	$ 0.0	$ 0.0	0.0	189.7	0.0
Other comprehensive income (loss)	1.1	0.0	0.0	0.0	0.0	1.1
Cash dividends	(59.1)	(0.0)	(0.0)	(0.0)	(59.1)	(0.0)
Stock based compensation expense and stock option plan transactions	49.3	$ 0.0	$ 42.2	7.1	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	1.2
Ending Balance at Jun. 30, 2020	$ 2,998.8	$ 292.8	$ (2,037.3)	$ 302.8	$ 4,538.8	$ (98.3)
Ending Balance (in shares) at Jun. 30, 2020		292.8	(45.9)