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, 2015		165.1
Balance at Dec. 31, 2015	$ 2,418.8	$ 165.1	$ 2,236.4	$ (492.5)	$ 509.8
Net income (loss)	(21.4)	0.0	0.0	0.0	(21.4)
Other comprehensive income	25.8	0.0	0.0	25.8	0.0
Dividends paid:
Common stock ($0.60 per share)	$ (99.1)	$ 0.0	0.0	0.0	(99.1)
Common stock issued for:
Stock options exercised (in shares)	0.1	0.0
Stock options exercised	$ 0.4	$ 0.0	0.4	0.0	0.0
Other Transactions (in shares)		0.2
Other Transactions	3.0	$ 0.2	2.8	0.0	0.0
Stock-based compensation	3.2	$ 0.0	3.2	0.0	0.0
Balance (in shares) at Sep. 30, 2016		165.3
Balance at Sep. 30, 2016	2,330.7	$ 165.3	2,242.8	(466.7)	389.3
Balance (in shares) at Dec. 31, 2016		165.4
Balance at Dec. 31, 2016	2,273.0	$ 165.4	2,243.8	(510.0)	373.8
Net income (loss)	60.2	0.0	0.0	0.0	60.2
Other comprehensive income	40.0	0.0	0.0	40.0	0.0
Dividends paid:
Common stock ($0.60 per share)	$ (99.6)	$ 0.0	0.0	0.0	(99.6)
Common stock issued for:
Stock options exercised (in shares)	1.0	1.0
Stock options exercised	$ 18.5	$ 1.0	17.5	0.0	0.0
Other Transactions (in shares)		0.0
Other Transactions	1.7	$ 0.0	1.7	0.0	0.0
Stock-based compensation	4.7	$ 0.0	4.7	0.0	0.0
Balance (in shares) at Sep. 30, 2017		166.4
Balance at Sep. 30, 2017	$ 2,298.5	$ 166.4	$ 2,267.7	$ (470.0)	$ 334.4