Unearned Revenue - Schedule of Unearned Revenue (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018
Deferred Revenue Arrangement [Line Items]
Unearned revenue	$ 3,448,581	$ 3,583,849
California [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	382,028	406,054
Northwest [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	362,225	315,582
Heavy Civil [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	2,287,770	2,399,785
Kenny [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	416,558	462,428
Construction Segment
Deferred Revenue Arrangement [Line Items]
Unearned revenue	880,976	825,428
Construction Segment | California [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	333,866	365,771
Construction Segment | Northwest [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	362,225	262,117
Construction Segment | Heavy Civil [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	54,596	43,016
Construction Segment | Kenny [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	130,289	154,524
Large Project Construction [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	2,567,605	2,758,421
Large Project Construction [Member] | California [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	48,162	40,283
Large Project Construction [Member] | Northwest [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue		53,465
Large Project Construction [Member] | Heavy Civil [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	2,233,174	2,356,769
Large Project Construction [Member] | Kenny [Member]
Deferred Revenue Arrangement [Line Items]
Unearned revenue	$ 286,269	$ 307,904