Operations by Business Segment and Geographic Area - External Revenue and Total Assets by Geographic Area (Details 7) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from external customers and long lived assets
Revenues	$ 4,370,700	$ 4,384,600	$ 4,810,100	$ 4,548,600	$ 5,455,200	$ 5,440,100	$ 5,251,700	$ 5,384,600	$ 18,114,048	$ 21,531,577	$ 27,351,573
Assets	7,631,506				8,194,429				7,631,506	8,194,429
United States
Revenues from external customers and long lived assets
Revenues									7,857,300	7,466,200	7,295,000
Assets	4,312,100				4,598,400				4,312,100	4,598,400
Canada
Revenues from external customers and long lived assets
Revenues									2,459,300	4,133,300	6,275,800
Assets	800,900				900,400				800,900	900,400
Asia Pacific (includes Australia)
Revenues from external customers and long lived assets
Revenues									870,400	2,568,000	4,503,400
Assets	541,200				724,700				541,200	724,700
Europe
Revenues from external customers and long lived assets
Revenues									2,509,200	2,070,100	2,096,300
Assets	1,364,600				1,178,000				1,364,600	1,178,000
Central and South America
Revenues from external customers and long lived assets
Revenues									2,560,400	2,494,800	3,509,700
Assets	251,700				371,700				251,700	371,700
Middle East and Africa
Revenues from external customers and long lived assets
Revenues									1,857,400	2,799,200	$ 3,671,400
Assets	$ 361,000				$ 421,200				$ 361,000	$ 421,200