Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 3,856	$ 2,142	$ 2,683
Other comprehensive income (loss):
Unrealized investment gains (losses), net of related offsets	4,165	(3,337)	2,502
Unrealized gains (losses) on derivatives	1,288	(691)	(241)
Foreign currency translation adjustments	(44)	22	(30)
Defined benefit plans adjustment	(1,001)	1,191	(766)
Other comprehensive income (loss), before income tax	4,408	(2,815)	1,465
Income tax (expense) benefit related to items of other comprehensive income (loss)	(1,532)us-gaap_OtherComprehensiveIncomeLossTax	965us-gaap_OtherComprehensiveIncomeLossTax	(511)us-gaap_OtherComprehensiveIncomeLossTax
Other comprehensive income (loss), net of income tax	2,876	(1,850)	954
Comprehensive income (loss)	6,732	292	3,637
Less: Comprehensive income (loss) attributable to noncontrolling interest, net of income tax	(5)	(7)	2
Comprehensive income (loss) attributable to Metropolitan Life Insurance Company	$ 6,737us-gaap_ComprehensiveIncomeNetOfTax	$ 299us-gaap_ComprehensiveIncomeNetOfTax	$ 3,635us-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 income tax of income (loss) including the portion attributable to nonredeemable noncontrolling interest. Excludes the portion attributable to redeemable noncontrolling interest recognized as temporary equity.

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Amount before tax, after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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

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Amount before tax, after 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 before tax, after 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 other comprehensive income (loss).

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Amount before tax, after reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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