Contingencies (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Accrual for environmental investigation and remediation activities	$ 6,800,000	$ 6,900,000	$ 5,000,000
Loss contingency, range of possible loss, minimum	0
Loss contingency, range of possible loss, maximum	$ 4,300,000