Litigation (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 12, 2015	Aug. 31, 2011
Loss Contingencies [Line Items]
Potential liabilities related to litigation and environmental matters	$ 27,400,000	$ 19,500,000	$ 20,700,000
Litigation related to construction materials [Member]
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss					$ 3,700,000
Additional amount per day of potential penalties					$ 5,000
Litigation related to construction services [Member]
Loss Contingencies [Line Items]
Damage repair estimate				$ 21,000,000