Non-operating Income (Expense) Disclosure (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Nonoperating Income (Expense) [Abstract]
Interest Expense									$ (48.0)	$ (54.4)	$ (60.8)
Amortization of debt charges									(1.5)	(2.6)	(3.1)
Capitalized interest									0.2	0.1	0
Interest expense, net of capitalized interest	(12.9)	(10.7)	(13.1)	(12.6)	(14.3)	(14.2)	(14.4)	(14.0)	(49.3)	(56.9)	(63.9)
Investment income									13.0	13.3	18.0
Realized gains from the sale of investments									0	15.2	19.0
SERP marketing adjustments									1.8	0.2	1.4
Investment income	3.1	4.1	3.4	4.2	4.5	16.7	3.5	4.0	14.8	28.7	38.4
Other than temporary impairment									0	(14.8)	(17.0)
Foreign currency gains (losses)									(2.7)	(1.0)	2.2
Gain on settlement of litigation related to ARS								(0.8)	(20.0)	0	0
Early debt extinguishment									52.2	0	0
Other non-operating expense									(34.9)	(1.0)	2.2
Total non-operating income (expense)	$ 19.6	$ 0.4	$ (54.8)	$ (0.1)	$ 0.6	$ (4.0)	$ 0.6	$ 1.8	$ (69.4)	$ (44.0)	$ (40.3)