Pension and Other Post-Retirement Benefit Plans Pension and Other Post-Retirement Benefit Plans (Defined Contribution Plans Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Line Items]
Nonelective contribution vesting period	3 years
Deferred compensation investments	$ 35.8	$ 41.6
FMC Technologies stock held in trust	8.0	7.7
Nonelective Contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Expenses recognized	18.9	16.2	11.8
Matching Contribution [Member]
Defined Contribution Plan Disclosure [Line Items]
Expenses recognized	28.4	23.5	18.4
Non Qualified Deferred Compensation Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Deferred compensation liability	38.5	38.5
Deferred compensation investments	$ 30.7	$ 29.1
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Requisite Service Period For Current Nonunion Employee	5 years