Business Segment Information (Schedule of Operations by Reportable Segment) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues									$ 5,639,000,000	$ 4,913,000,000	$ 4,171,000,000
Gross profit (loss)	$ 171,000,000	$ 169,000,000	$ 160,000,000	$ 153,000,000	$ 157,000,000	$ 149,000,000	$ 161,000,000	$ 117,000,000	653,000,000	584,000,000	439,000,000
Equity in earnings of unconsolidated affiliates	11,000,000	9,000,000	15,000,000	0	29,000,000	17,000,000	12,000,000	21,000,000	35,000,000	79,000,000	70,000,000
Selling, general and administrative expenses									(341,000,000)	(294,000,000)	(244,000,000)
Acquisition and integration related costs									(2,000,000)	(7,000,000)	0
Asset impairment and restructuring charges									0	0	(6,000,000)
Gain (loss) on disposition of assets									17,000,000	(2,000,000)	5,000,000
Gain on consolidation of Aspire entities									0	108,000,000	0
Segment operating income (loss)	$ 88,000,000	$ 104,000,000	$ 92,000,000	$ 78,000,000	$ 90,000,000	$ 99,000,000	$ 100,000,000	$ 179,000,000	362,000,000	468,000,000	264,000,000
Capital expenditures									20,000,000	17,000,000	8,000,000
Depreciation and amortization									104,000,000	63,000,000	48,000,000
Operating Segments | Government Solutions
Segment Reporting Information [Line Items]
Revenues									3,925,000,000	3,457,000,000	2,193,000,000
Gross profit (loss)									430,000,000	350,000,000	188,000,000
Equity in earnings of unconsolidated affiliates									29,000,000	32,000,000	43,000,000
Selling, general and administrative expenses									(134,000,000)	(109,000,000)	(57,000,000)
Acquisition and integration related costs									(2,000,000)	(7,000,000)	0
Asset impairment and restructuring charges									0	0	0
Gain (loss) on disposition of assets									12,000,000	4,000,000	0
Gain on consolidation of Aspire entities									0	113,000,000	0
Segment operating income (loss)									335,000,000	383,000,000	173,000,000
Capital expenditures									7,000,000	11,000,000	4,000,000
Depreciation and amortization									58,000,000	42,000,000	27,000,000
Operating Segments | Technology Solutions
Segment Reporting Information [Line Items]
Revenues									374,000,000	297,000,000	269,000,000
Gross profit (loss)									118,000,000	106,000,000	98,000,000
Equity in earnings of unconsolidated affiliates									0	0	0
Selling, general and administrative expenses									(28,000,000)	(24,000,000)	(25,000,000)
Acquisition and integration related costs									0	0	0
Asset impairment and restructuring charges									0	0	0
Gain (loss) on disposition of assets									0	0	0
Gain on consolidation of Aspire entities									0	0	0
Segment operating income (loss)									90,000,000	82,000,000	73,000,000
Capital expenditures									1,000,000	0	0
Depreciation and amortization									6,000,000	3,000,000	3,000,000
Operating Segments | Energy Solutions
Segment Reporting Information [Line Items]
Revenues									1,339,000,000	1,157,000,000	1,671,000,000
Gross profit (loss)									100,000,000	134,000,000	153,000,000
Equity in earnings of unconsolidated affiliates									19,000,000	50,000,000	27,000,000
Selling, general and administrative expenses									(63,000,000)	(64,000,000)	(68,000,000)
Acquisition and integration related costs									0	0	0
Asset impairment and restructuring charges									0	0	(6,000,000)
Gain (loss) on disposition of assets									0	(2,000,000)	5,000,000
Gain on consolidation of Aspire entities									0	0	0
Segment operating income (loss)									56,000,000	118,000,000	111,000,000
Capital expenditures									3,000,000	1,000,000	2,000,000
Depreciation and amortization									21,000,000	10,000,000	10,000,000
Other
Segment Reporting Information [Line Items]
Selling, general and administrative expenses									(116,000,000)	(97,000,000)	(94,000,000)
Acquisition and integration related costs									0	0	0
Asset impairment and restructuring charges									0	0	0
Gain (loss) on disposition of assets									5,000,000	(4,000,000)	0
Gain on consolidation of Aspire entities									0	(5,000,000)	0
Segment operating income (loss)									(111,000,000)	(106,000,000)	(93,000,000)
Capital expenditures									9,000,000	5,000,000	2,000,000
Depreciation and amortization									19,000,000	8,000,000	8,000,000
Subtotal
Segment Reporting Information [Line Items]
Revenues									5,638,000,000	4,911,000,000	4,133,000,000
Gross profit (loss)									648,000,000	590,000,000	439,000,000
Equity in earnings of unconsolidated affiliates									48,000,000	82,000,000	70,000,000
Selling, general and administrative expenses									(341,000,000)	(294,000,000)	(244,000,000)
Acquisition and integration related costs									(2,000,000)	(7,000,000)	0
Asset impairment and restructuring charges									0	0	(6,000,000)
Gain (loss) on disposition of assets									17,000,000	(2,000,000)	5,000,000
Gain on consolidation of Aspire entities									0	108,000,000	0
Segment operating income (loss)									370,000,000	477,000,000	264,000,000
Capital expenditures									20,000,000	17,000,000	8,000,000
Depreciation and amortization									104,000,000	63,000,000	48,000,000
Non-strategic Business
Segment Reporting Information [Line Items]
Revenues									1,000,000	2,000,000	38,000,000
Gross profit (loss)									5,000,000	(6,000,000)	0
Equity in earnings of unconsolidated affiliates									(13,000,000)	(3,000,000)	0
Selling, general and administrative expenses									0	0	0
Acquisition and integration related costs									0	0	0
Asset impairment and restructuring charges									0	0	0
Gain (loss) on disposition of assets									0	0	0
Gain on consolidation of Aspire entities									0	0	0
Segment operating income (loss)									(8,000,000)	(9,000,000)	0
Capital expenditures									0	0	0
Depreciation and amortization									$ 0	$ 0	$ 0