Condensed Consolidated Statements Of Comprehensive Income (Loss) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 51us-gaap_ProfitLoss	$ (20)us-gaap_ProfitLoss
Net cumulative translation adjustments (CTA)[Abstract]
Foreign currency translation adjustments, net of tax	(58)	9
Reclassification adjustment included in net income	0	0
Foreign currency translation adjustments, net of taxes of $1 and $3	(58)	9
Actuarial losses, net of tax	0	1
Reclassification adjustment included in net income	12	8
Pension and post-retirement benefits, net of taxes of $1 and $3	12	9
Unrealized gains (losses) on derivatives:
Changes in fair value of derivatives, net of tax	0	(1)
Reclassification adjustment included in net income	0	0
Changes in fair value of derivatives, net of taxes of $0 and $0	0	(1)
Other comprehensive income (loss), net of tax	(46)	17
Comprehensive income (loss)	5	(3)
Less: Comprehensive income attributable to noncontrolling interests	(7)	(23)
Comprehensive loss attributable to KBR	$ (2)us-gaap_ComprehensiveIncomeNetOfTax	$ (26)us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of (increase) decrease in the value of the projected benefit obligation related to a change in an actuarial assumption and increase (decrease) in the value of the plan assets resulting from experience different from that assumed, that has not been recognized in net periodic benefit (cost) credit.

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Amount after tax, before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax of reclassification adjustment from accumulated other comprehensive income for translation gain (loss) realized upon the sale or liquidation of an investment in a foreign entity and foreign currency hedges that are designated and qualified as hedging instruments for hedges of the foreign currency exposure of a net investment in a foreign operation.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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