The following tables present information about industry segments and geographic areas for the years ended December 31, 2015, 2014 and 2013 (in thousands):



	2015			2014			2013
Revenues from unrelated entities:
United States electrical construction and facilities services	$	1,367,142		$	1,311,988		$	1,345,750
United States mechanical construction and facilities services	2,312,763			2,201,212			2,329,834
United States building services	1,739,259			1,721,341			1,794,978
United States industrial services	922,085			839,980			519,413
Total United States operations	6,341,249			6,074,521			5,989,975
United Kingdom building services	377,477			350,444			343,552
Total worldwide operations	$	6,718,726		$	6,424,965		$	6,333,527

Total revenues:
United States electrical construction and facilities services	$	1,378,620		$	1,326,547		$	1,371,979
United States mechanical construction and facilities services	2,326,683			2,219,886			2,387,072
United States building services	1,794,086			1,762,697			1,839,129
United States industrial services	923,648			842,040			522,417
Less intersegment revenues	(81,788		)	(76,649		)	(130,622		)
Total United States operations	6,341,249			6,074,521			5,989,975
United Kingdom building services	377,477			350,444			343,552
Total worldwide operations	$	6,718,726		$	6,424,965		$	6,333,527



Operating income (loss):
United States electrical construction and facilities services	$	82,225		$	90,873		$	98,114
United States mechanical construction and facilities services	138,688			114,418			93,765
United States building services	70,532			65,885			67,225
United States industrial services	56,469			63,159			38,763
Total United States operations	347,914			334,335			297,867
United Kingdom building services	11,634			15,011			13,021
Corporate administration	(71,642		)	(68,578		)	(69,891		)
Restructuring expenses	(824		)	(1,168		)	(647		)
Impairment loss on identifiable intangible assets	—			(1,471		)	—
Gain on sale of building	—			11,749			—
Total worldwide operations	287,082			289,878			240,350
Other corporate items:
Interest expense	(8,932		)	(9,075		)	(8,769		)
Interest income	673			842			1,128
Income from continuing operations before income taxes	$	278,823		$	281,645		$	232,709



	2015		2014		2013
Capital expenditures:
United States electrical construction and facilities services	$	6,063	$	6,671	$	6,164
United States mechanical construction and facilities services	5,345		8,631		8,866
United States building services	7,233		10,589		7,579
United States industrial services	11,073		9,139		10,281
Total United States operations	29,714		35,030		32,890
United Kingdom building services	5,298		1,935		1,536
Corporate administration	448		1,070		1,071
Total worldwide operations	$	35,460	$	38,035	$	35,497

Depreciation and amortization of Property, plant and equipment:
United States electrical construction and facilities services	$	4,676	$	4,237	$	3,640
United States mechanical construction and facilities services	7,624		7,600		7,280
United States building services	9,834		10,660		11,288
United States industrial services	9,629		9,839		8,781
Total United States operations	31,763		32,336		30,989
United Kingdom building services	3,603		3,305		4,477
Corporate administration	928		883		844
Total worldwide operations	$	36,294	$	36,524	$	36,310



Costs and estimated earnings in excess of billings on uncompleted contracts:
United States electrical construction and facilities services	$	39,116	$	32,464	$	28,988
United States mechanical construction and facilities services	46,220		43,443		38,804
United States building services	20,959		18,555		14,957
United States industrial services	3,358		281		5
Total United States operations	109,653		94,743		82,754
United Kingdom building services	8,081		8,458		7,973
Total worldwide operations	$	117,734	$	103,201	$	90,727

Billings in excess of costs and estimated earnings on uncompleted contracts:
United States electrical construction and facilities services	$	139,857	$	114,422	$	118,458
United States mechanical construction and facilities services	238,463		199,983		205,974
United States building services	44,476		38,059		30,827
United States industrial services	1,170		1,516		805
Total United States operations	423,966		353,980		356,064
United Kingdom building services	5,269		14,575		25,231
Total worldwide operations	$	429,235	$	368,555	$	381,295



	2015		2014		2013
Long-lived assets:
United States electrical construction and facilities services	$	20,139	$	18,792	$	16,512
United States mechanical construction and facilities services	296,633		288,161		293,790
United States building services	378,367		392,364		406,498
United States industrial services	730,413		750,101		772,209
Total United States operations	1,425,552		1,449,418		1,489,009
United Kingdom building services	10,927		6,899		8,831
Corporate administration	1,543		2,023		1,896
Total worldwide operations	$	1,438,022	$	1,458,340	$	1,499,736



Total assets:
United States electrical construction and facilities services	$	372,525	$	332,150	$	329,742
United States mechanical construction and facilities services	894,366		793,056		795,256
United States building services	721,653		737,082		756,785
United States industrial services	883,338		954,018		940,916
Total United States operations	2,871,882		2,816,306		2,822,699
United Kingdom building services	133,782		130,340		160,828
Corporate administration	540,806		442,321		482,388
Total worldwide operations	$	3,546,470	$	3,388,967	$	3,465,915