Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement And Statement Of Comprehensive Income [Abstract]
Revenues	$ 5,639	$ 4,913	$ 4,171
Cost of revenues	(4,986)	(4,329)	(3,732)
Gross profit	653	584	439
Equity in earnings of unconsolidated affiliates	35	79	70
Selling, general and administrative expenses	(341)	(294)	(244)
Acquisition and integration related costs	(2)	(7)	0
Asset impairment and restructuring charges	0	0	(6)
(Gain) loss on disposition of assets	17	(2)	5
Gain on consolidation of Aspire subcontracting entities	0	108	0
Operating income	362	468	264
Interest expense	(99)	(66)	(21)
Other non-operating income (loss)	5	(6)	4
Income before income taxes and noncontrolling interests	268	396	247
(Provision) benefit for income taxes	(59)	(86)	193
Net income	209	310	440
Net income attributable to noncontrolling interests	(7)	(29)	(8)
Net income attributable to KBR	$ 202	$ 281	$ 432
Net income attributable to KBR per share:
Basic (usd per share)	$ 1.42	$ 1.99	$ 3.05
Diluted (usd per share)	$ 1.41	$ 1.99	$ 3.05
Basic weighted average common shares outstanding (in shares)	141	140	141
Diluted weighted average common shares outstanding (in shares)	142	141	141
Cash dividends declared per share (usd per share)	$ 0.32	$ 0.32	$ 0.32
Net income	$ 209	$ 310	$ 440
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of taxes of $1, $(2) and $6	(11)	(45)	2
Pension and post-retirement benefits, net of taxes of $11, $(14) and $(27)	(62)	68	125
Changes in fair value of derivatives, net of taxes of $2	(4)
Changes in fair value of derivatives, net of taxes of $3 and $0, before 2017-12 adoption		(11)	0
Total other comprehensive income (loss)	(77)	12	127
Comprehensive income	132	322	567
Less: Comprehensive income attributable to noncontrolling interests	7	29	7
Comprehensive income attributable to KBR	$ 125	$ 293	$ 560