Condensed Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Balance (in shares) at Dec. 31, 2017		167.1
Balance at Dec. 31, 2017	$ 2,753.7	$ 167.1	$ 2,280.9	$ (484.6)	$ 790.3
Income tax reclassification adjustment	0.0	0.0	0.0	(85.9)	85.9
Net (loss) income	20.9	0.0	0.0	0.0	20.9
Other comprehensive (loss) income	17.7	0.0	0.0	17.7	0.0
Dividends paid:
Common stock ($0.20 per share)	(33.4)	$ 0.0	0.0	0.0	(33.4)
Common stock issued for:
Stock options exercised (in shares)		0.1
Stock options exercised	1.0	$ 0.1	0.9	0.0	0.0
Other Transactions (in shares)		0.0
Other Transactions	0.5	$ 0.0	0.5	0.0	0.0
Stock-based compensation	2.7	$ 0.0	2.7	0.0	0.0
Balance (in shares) at Mar. 31, 2018		167.2
Balance at Mar. 31, 2018	2,763.1	$ 167.2	2,285.0	(552.8)	863.7
Balance (in shares) at Dec. 31, 2017		167.1
Balance at Dec. 31, 2017	2,753.7	$ 167.1	2,280.9	(484.6)	790.3
Net (loss) income	79.5
Other comprehensive (loss) income	$ (2.7)
Common stock issued for:
Stock options exercised (in shares)	0.2
Stock options exercised	$ 2.2
Balance (in shares) at Jun. 30, 2018		167.0
Balance at Jun. 30, 2018	2,763.1	$ 167.0	2,280.5	(573.2)	888.8
Balance (in shares) at Mar. 31, 2018		167.2
Balance at Mar. 31, 2018	2,763.1	$ 167.2	2,285.0	(552.8)	863.7
Net (loss) income	58.6	0.0	0.0	0.0	58.6
Other comprehensive (loss) income	(20.4)	0.0	0.0	(20.4)	0.0
Dividends paid:
Common stock ($0.20 per share)	(33.5)	$ 0.0	0.0	0.0	(33.5)
Common stock repurchased and retired (in shares)		(0.3)
Common stock repurchased and retired	(9.1)	$ (0.3)	(8.8)	0.0	0.0
Common stock issued for:
Stock options exercised (in shares)		0.1
Stock options exercised	1.2	$ 0.1	1.1	0.0	0.0
Other Transactions (in shares)		0.0
Other Transactions	0.1	$ 0.0	0.1	0.0	0.0
Stock-based compensation	3.1	$ 0.0	3.1	0.0	0.0
Balance (in shares) at Jun. 30, 2018		167.0
Balance at Jun. 30, 2018	2,763.1	$ 167.0	2,280.5	(573.2)	888.8
Balance (in shares) at Dec. 31, 2018		165.3
Balance at Dec. 31, 2018	2,832.2	$ 165.3	2,247.4	(651.0)	1,070.5
Lease accounting adoption adjustment	11.2	0.0	0.0	0.0	11.2
Net (loss) income	41.7	0.0	0.0	0.0	41.7
Other comprehensive (loss) income	(5.9)	0.0	0.0	(5.9)	0.0
Dividends paid:
Common stock ($0.20 per share)	(33.0)	$ 0.0	0.0	0.0	(33.0)
Common stock repurchased and retired (in shares)		(0.6)
Common stock repurchased and retired	(13.2)	$ (0.6)	(12.6)	0.0	0.0
Common stock issued for:
Stock options exercised (in shares)		0.1
Stock options exercised	1.4	$ 0.1	1.3	0.0	0.0
Other Transactions (in shares)		0.1
Other Transactions	0.4	$ 0.1	0.3	0.0	0.0
Stock-based compensation	2.8	$ 0.0	2.8	0.0	0.0
Balance (in shares) at Mar. 31, 2019		164.9
Balance at Mar. 31, 2019	2,837.6	$ 164.9	2,239.2	(656.9)	1,090.4
Balance (in shares) at Dec. 31, 2018		165.3
Balance at Dec. 31, 2018	2,832.2	$ 165.3	2,247.4	(651.0)	1,070.5
Net (loss) income	21.7
Other comprehensive (loss) income	$ (9.4)
Common stock issued for:
Stock options exercised (in shares)	0.1
Stock options exercised	$ 1.5
Balance (in shares) at Jun. 30, 2019		164.3
Balance at Jun. 30, 2019	2,770.8	$ 164.3	2,229.2	(660.4)	1,037.7
Balance (in shares) at Mar. 31, 2019		164.9
Balance at Mar. 31, 2019	2,837.6	$ 164.9	2,239.2	(656.9)	1,090.4
Net (loss) income	(20.0)	0.0	0.0	0.0	(20.0)
Other comprehensive (loss) income	(3.5)	0.0	0.0	(3.5)	0.0
Dividends paid:
Common stock ($0.20 per share)	(32.7)	$ 0.0	0.0	0.0	(32.7)
Common stock repurchased and retired (in shares)		(0.6)
Common stock repurchased and retired	(13.5)	$ (0.6)	(12.9)	0.0	0.0
Common stock issued for:
Stock options exercised (in shares)		0.0
Stock options exercised	0.1	$ 0.0	0.1	0.0	0.0
Other Transactions (in shares)		0.0
Other Transactions	0.9	$ 0.0	0.9	0.0	0.0
Stock-based compensation	1.9	$ 0.0	1.9	0.0	0.0
Balance (in shares) at Jun. 30, 2019		164.3
Balance at Jun. 30, 2019	$ 2,770.8	$ 164.3	$ 2,229.2	$ (660.4)	$ 1,037.7