Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	12 Months Ended			12 Months Ended
	Apr. 17, 2012	Dec. 31, 2012	Dec. 31, 2011	Feb. 29, 2012	Dec. 31, 2011 Liftboats [Member]	Dec. 31, 2010 Liftboats [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additional contingent consideration recorded in the statement of operations		$ 2.0
Percentage of limited partnership interest	10.00%	10.00%
Adjustment Interval of Variable Rate on Interest Rate Swap		90
Number of shares comprising Available for Sale Securities	7.0	1.4
Interest rate swap agreement for notional amount		100	150	150
Selling of interest rate swap				1.2
Fair value of debt		1,960.0	1,749.8
Contingent consideration		9.9
Impairment of long lived assets			$ 35.8		$ 46.1	$ 32.0