Goodwill and Other Intangible Assets (Changes in Carrying Amount of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Balance at beginning of period	$ 585,006	$ 577,756
Activity		7,250
Balance at end of period	$ 585,006	585,006
Civil [Member]
Balance at beginning of period	415,358	415,358
Accumulated Impairment	$ 76,700	76,700	$ 76,700
Activity
Balance at end of period	$ 415,358	415,358
Building [Member]
Balance at beginning of period	13,455	13,455
Accumulated Impairment	$ 411,300	411,300	$ 411,300
Activity
Balance at end of period	$ 13,455	13,455
Specialty Contractors [Member]
Balance at beginning of period	$ 156,193	148,943
Activity		7,250
Balance at end of period	$ 156,193	$ 156,193