Employee Benefit Plans (Details 4) (USD $) In Millions, unless otherwise specified				12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Level 3 [Member]	Dec. 31, 2012 Level 3 [Member]	Dec. 31, 2013 Level 3 [Member] Royalty Rights [Member]	Dec. 31, 2012 Level 3 [Member] Royalty Rights [Member]	Dec. 31, 2013 Level 3 [Member] Private Equity [Member]	Dec. 31, 2012 Level 3 [Member] Private Equity [Member]
Summary of changes in Level 3 Trust investments
Fair value of plan assets as of January 1,	$ 295.8	$ 316.7	$ 301.7	$ 23.8	$ 13.6	$ 21.4	$ 11.4	$ 2.4	$ 2.2
Actual return on plan assets relating to assets still held as of the reporting date				2.6	1.7	2.3	1.6	0.3	0.1
Actual return on plan assets relating to assets sold during the year				1.7	0.7	1.6	0.8	0.1	(0.1)
Net purchases and sales				(2.2)	7.8	(2.0)	7.6	(0.2)	0.2
Fair value of plan assets as of December 31,	$ 295.8	$ 316.7	$ 301.7	$ 25.9	$ 23.8	$ 23.3	$ 21.4	$ 2.6	$ 2.4