Summary of Significant Accounting Policies (Costs and Estimated Earnings in Excess of Billings) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Summary of Significant Accounting Policies [Abstract]
Claims	$ 407,164	$ 311,949
Unapproved change orders	270,019	161,375
Other unbilled costs and profits	227,992	253,078
Total costs and estimated earnings in excess of billings	$ 905,175	$ 726,402