Business Segments (Data by Geographic Region) (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
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 318.2	$ 210.1	$ 171.4	$ 173.7	$ 273.9	$ 194.6	$ 163.0	$ 158.9	$ 873.4	$ 790.4	$ 885.6
Long-lived assets	203.2				129.2				203.2	129.2	129.3
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									746.8	662.0	770.8
Long-lived assets	197.1				124.2				197.1	124.2	125.1
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									126.6	128.4	114.8
Long-lived assets	6.1				5.0				6.1	5.0	4.2
HBB
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	181.2	124.8	110.7	104.9	161.4	126.7	104.3	100.6	521.6	493.0	515.7
NACoal
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 50.9	$ 38.0	$ 19.2	$ 24.3	$ 23.5	$ 21.0	$ 19.4	$ 17.9	$ 132.4	$ 81.8	$ 156.8