Property and Equipment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Long Lived Assets Held-for-sale [Line Items]
Depreciation	$ 6.7	$ 5.4
Impairment of long-lived assets held-for-use	6.4
Other Nonoperating Income (Expense)
Long Lived Assets Held-for-sale [Line Items]
Impairment of long-lived assets held-for-use	0.9
Heavy Civil Marine Construction | Other Nonoperating Income (Expense)
Long Lived Assets Held-for-sale [Line Items]
Impairment of long-lived assets to be disposed of	$ 1.7