SEGMENT INFORMATION

We have the following reportable segments: (a) United States electrical construction and facilities services (involving systems for electrical power transmission and distribution; premises electrical and lighting systems; process instrumentation in the refining, chemical process, food process and mining industries; low-voltage systems, such as fire alarm, security and process control; voice and data communication; roadway and transit lighting; and fiber optic lines); (b) United States mechanical construction and facilities services (involving systems for heating, ventilation, air conditioning, refrigeration and clean-room process ventilation; fire protection; plumbing, process and high-purity piping; controls and filtration; water and wastewater treatment and central plant heating and cooling; cranes and rigging; millwrighting; and steel fabrication, erection and welding); (c) United States building services; (d) United States industrial services; and (e) United Kingdom building services. The “United States building services” and “United Kingdom building services” segments principally consist of those operations which provide a portfolio of services needed to support the operation and maintenance of customers’ facilities, including commercial and government site-based operations and maintenance; facility maintenance and services, including reception, security and catering services; outage services to utilities and industrial plants; military base operations support services; mobile maintenance and services; floor care and janitorial services; landscaping, lot sweeping and snow removal; facilities management; vendor management; call center services; installation and support for building systems; program development, management and maintenance for energy systems; technical consulting and diagnostic services; infrastructure and building projects for federal, state and local governmental agencies and bodies; and small modification and retrofit projects, which services are not generally related to customers’ construction programs. The “United States industrial services” segment principally consists of those operations which provide industrial maintenance and services, including those for refineries and petrochemical plants, including on-site repairs, maintenance and service of heat exchangers, towers, vessels and piping; design, manufacturing, repair and hydro blast cleaning of shell and tube heat exchangers and related equipment; refinery turnaround planning and engineering services; specialty welding services; overhaul and maintenance of critical process units in refineries and petrochemical plants; and specialty technical services for refineries and petrochemical plants.

The following tables present information about industry segments and geographic areas for the years ended December 31, 2017, 2016 and 2015 (in thousands):



	2017			2016			2015
Revenues from unrelated entities:
United States electrical construction and facilities services	$	1,829,567		$	1,704,403		$	1,367,142
United States mechanical construction and facilities services	2,963,815			2,643,321			2,293,038
United States building services	1,753,703			1,810,229			1,758,984
United States industrial services	799,169			1,067,315			922,085
Total United States operations	7,346,254			7,225,268			6,341,249
United Kingdom building services	340,745			326,256			377,477
Total worldwide operations	$	7,686,999		$	7,551,524		$	6,718,726

Total revenues:
United States electrical construction and facilities services	$	1,836,985		$	1,728,920		$	1,378,620
United States mechanical construction and facilities services	2,994,700			2,662,100			2,306,958
United States building services	1,812,763			1,864,824			1,813,811
United States industrial services	801,531			1,068,662			923,648
Less intersegment revenues	(99,725		)	(99,238		)	(81,788		)
Total United States operations	7,346,254			7,225,268			6,341,249
United Kingdom building services	340,745			326,256			377,477
Total worldwide operations	$	7,686,999		$	7,551,524		$	6,718,726



Operating income (loss):
United States electrical construction and facilities services	$	150,001		$	101,761		$	82,225
United States mechanical construction and facilities services	212,320			132,667			138,444
United States building services	81,504			76,845			70,776
United States industrial services	19,084			77,845			56,469
Total United States operations	462,909			389,118			347,914
United Kingdom building services	14,849			11,946			11,634
Corporate administration	(87,808		)	(88,740		)	(71,642		)
Restructuring expenses	(1,577		)	(1,438		)	(824		)
Impairment loss on goodwill and identifiable intangible assets	(57,819		)	(2,428		)	—
Total worldwide operations	330,554			308,458			287,082
Other corporate items:
Interest expense	(12,770		)	(12,627		)	(8,932		)
Interest income	965			663			673
Income from continuing operations before income taxes	$	318,749		$	296,494		$	278,823



	2017		2016		2015
Capital expenditures:
United States electrical construction and facilities services	$	4,797	$	5,294	$	6,063
United States mechanical construction and facilities services	6,778		7,672		5,312
United States building services	10,745		11,080		7,266
United States industrial services	9,583		10,065		11,073
Total United States operations	31,903		34,111		29,714
United Kingdom building services	2,166		4,523		5,298
Corporate administration	615		1,014		448
Total worldwide operations	$	34,684	$	39,648	$	35,460

Depreciation and amortization of Property, plant and equipment:
United States electrical construction and facilities services	$	6,545	$	6,318	$	4,676
United States mechanical construction and facilities services	7,819		7,544		7,562
United States building services	11,051		10,241		9,896
United States industrial services	10,274		10,394		9,629
Total United States operations	35,689		34,497		31,763
United Kingdom building services	3,371		3,560		3,603
Corporate administration	855		824		928
Total worldwide operations	$	39,915	$	38,881	$	36,294



Costs and estimated earnings in excess of billings on uncompleted contracts:
United States electrical construction and facilities services	$	35,060	$	46,193	$	39,116
United States mechanical construction and facilities services	52,381		46,703		45,787
United States building services	26,028		28,084		21,392
United States industrial services	1,636		2,572		3,358
Total United States operations	115,105		123,552		109,653
United Kingdom building services	7,516		7,145		8,081
Total worldwide operations	$	122,621	$	130,697	$	117,734

Billings in excess of costs and estimated earnings on uncompleted contracts:
United States electrical construction and facilities services	$	178,454	$	163,794	$	139,857
United States mechanical construction and facilities services	290,216		271,811		237,623
United States building services	48,481		50,546		45,316
United States industrial services	3,098		1,823		1,170
Total United States operations	520,249		487,974		423,966
United Kingdom building services	3,907		1,268		5,269
Total worldwide operations	$	524,156	$	489,242	$	429,235



	2017		2016		2015
Long-lived assets:
United States electrical construction and facilities services	$	180,990	$	183,632	$	20,139
United States mechanical construction and facilities services	352,970		287,744		294,969
United States building services	409,718		401,154		380,031
United States industrial services	630,184		709,267		730,413
Total United States operations	1,573,862		1,581,797		1,425,552
United Kingdom building services	11,729		11,446		10,927
Corporate administration	1,494		1,734		1,543
Total worldwide operations	$	1,587,085	$	1,594,977	$	1,438,022



Total assets:
United States electrical construction and facilities services	$	617,471	$	631,581	$	372,525
United States mechanical construction and facilities services	1,097,240		954,633		888,322
United States building services	764,085		753,434		727,697
United States industrial services	772,899		850,434		883,338
Total United States operations	3,251,695		3,190,082		2,871,882
United Kingdom building services	131,806		105,081		133,782
Corporate administration	582,403		557,275		501,042
Total worldwide operations	$	3,965,904	$	3,852,438	$	3,506,706

During 2017, we recognized $18.1 million of gross profit associated with the recovery of certain contract costs previously disputed on a project completed in the prior year. During 2016, we incurred $19.4 million of losses on a transportation project within our United States electrical construction and facilities services segment as a result of productivity issues attributable to unfavorable job-site conditions. In addition, within the United States mechanical construction and facilities services segment, we incurred $18.3 million of losses on a project at a process facility as a result of a contract dispute with our customer and $9.6 million of losses on an institutional project due to project delays and unfavorable job-site conditions. The results of our United States mechanical construction and facilities services segment included revenues of $12.1 million recognized during 2015 as a result of the settlement of a claim on an institutional project located in the Southeastern region of the United States.