Unearned Revenue (Tables)

12 Months Ended

Dec. 31, 2018

Deferred Revenue Disclosure [Abstract]

Schedule of Unearned Revenue

The following tables present our unearned revenue as of the respective periods (in thousands):

December 31, 2018
	Transportation		Water		Specialty		Total
California	$	314,261	$	6,163	$	57,820	$	378,244
Northwest		319,589		786		81,951		402,326
Heavy Civil		1,473,455		21,951		—		1,495,387
Federal		—		—		130,644		130,663
Midwest		78,004		211		203,601		281,816
Water and Mineral Services		—		189,597		—		189,597
Total	$	2,185,309	$	218,708	$	474,016	$	2,878,033
January 1, 2018
	Transportation		Water		Specialty		Total
California	$	299,552	$	27,328	$	79,176	$	406,056
Northwest		273,864		2,606		39,112		315,582
Heavy Civil		2,194,430		38,183		—		2,232,613
Federal		317		4,212		162,641		167,170
Midwest		90,584		1,961		365,767		458,312
Water and Mineral Services		—		4,116		—		4,116
Total	$	2,858,747	$	78,406	$	646,696	$	3,583,849

The components of the contract asset balances as of the respective dates were as follows (in thousands):

	December 31, 2018		January 1, 2018
Costs in excess of billings and estimated earnings	$	120,223	$	69,755
Contract retention		99,531		91,135
Total contract assets	$	219,754	$	160,890

The following table summarizes changes in the contract asset balance for the period presented (in thousands):

Balance at January 1, 2018	$	160,890
Change in the measure of progress on projects, net		911,109
Acquired contract assets		45,353
Revisions in estimates, net		(11,180	)
Billings		(823,286	)
Receipts related to contract retention		(63,132	)
Balance at December 31, 2018	$	219,754

The components of the contract liability balances as of the respective dates were as follows (in thousands):

	December 31, 2018		January 1, 2018
Billings in excess of costs and estimated earnings, net of retention	$	103,250	$	82,750
Provisions for losses		2,199		924
Total contract liabilities	$	105,449	$	83,674

The following table summarizes changes in the contract liability balance for the period presented (in thousands):

Balance at January 1, 2018	$	83,674
Change in the measure of progress on projects, net		(1,332,400	)
Acquired contract liabilities		7,974
Revisions in estimates, net		(4,450	)
Billings		1,349,441
Change in provision for loss, net		1,210
Balance at December 31, 2018	$	105,449