Related Party Transactions (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Chairman and Chief Executive Officer
Related party transactions
Monthly payments under non-cancelable operating lease agreements	$ 0.2
Percentage increase per annum in monthly lease payments under non-cancelable operating lease agreements	3.00%
Lease expense under non-cancelable operating lease agreements	2.5	2.3	2.3
O&G
Related party transactions
Ownership percentage in joint venture	30.00%
Estimated total contract value	368
Expenses incurred with related party	6.9	6.3	2.9
Number of Company's shares of common stock held by related party joint venture partner (in shares)	600,000	600,000
Percentage of common stock held by related party	1.24%	1.26%
JF Aviation, LLC
Related party transactions
Expenses incurred with related party		$ 0.4