Investments (Investment Income Net of Related Expenses) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Major Categories Of Investment Income Net Of Expenses [Line Items]
Gross Investment Income, Operating	$ 1,776,011us-gaap_GrossInvestmentIncomeOperating	$ 1,751,891us-gaap_GrossInvestmentIncomeOperating	$ 1,475,396us-gaap_GrossInvestmentIncomeOperating
Investment Income, Investment Expense	(62,320)	(52,026)	(39,190)
Investment income, net of related expenses	1,713,691us-gaap_NetInvestmentIncome	1,699,865us-gaap_NetInvestmentIncome	1,436,206us-gaap_NetInvestmentIncome
Available-for-sale Securities [Member]
Major Categories Of Investment Income Net Of Expenses [Line Items]
Gross Investment Income, Operating	1,052,715	966,759	868,682
Mortgage Loans on Real Estate [Member]
Major Categories Of Investment Income Net Of Expenses [Line Items]
Gross Investment Income, Operating	148,417	121,476	96,901
Policy Loans [Member]
Major Categories Of Investment Income Net Of Expenses [Line Items]
Gross Investment Income, Operating	55,248	57,099	62,855
Funds Withheld At Interest [Member]
Major Categories Of Investment Income Net Of Expenses [Line Items]
Gross Investment Income, Operating	447,364	545,550	393,586
Short-term Investments [Member]
Major Categories Of Investment Income Net Of Expenses [Line Items]
Gross Investment Income, Operating	2,118	2,236	4,173
Other Aggregated Investments [Member]
Major Categories Of Investment Income Net Of Expenses [Line Items]
Gross Investment Income, Operating	$ 70,149	$ 58,771	$ 49,199

Name:	rga_MajorCategoriesOfInvestmentIncomeNetOfExpensesLineItems
Namespace Prefix:	rga_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 2

-Article 7

+ Details

Name:	us-gaap_GrossInvestmentIncomeOperating
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of expenses related to the generation of investment income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.9)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

Name:	us-gaap_InvestmentIncomeInvestmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 16

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 2

-Article 7

+ Details

Name:	us-gaap_NetInvestmentIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	rga_MajorCategoriesOfInvestmentsAxis=rga_FundsWithheldAtInterestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rga_MajorCategoriesOfInvestmentsAxis=us-gaap_AvailableforsaleSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rga_MajorCategoriesOfInvestmentsAxis=us-gaap_MortgageLoansOnRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rga_MajorCategoriesOfInvestmentsAxis=us-gaap_OtherAggregatedInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rga_MajorCategoriesOfInvestmentsAxis=us-gaap_PolicyLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rga_MajorCategoriesOfInvestmentsAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: