Insurance Contract Liabilities and Investment Contract Liabilities - Gross Claims and Benefits Paid (Details) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Insurance Contracts [Abstract]
Maturities and surrenders	$ 3,750	$ 3,205
Annuity payments	2,124	2,017
Death and disability benefits	4,950	4,876
Health benefits	9,588	7,246
Policyholder dividends and interest on claims and deposits	1,632	1,378
Total gross claims and benefits paid	$ 22,044	$ 18,722

Expense For Policyholder Claims And Benefits Paid, Without Reduction For Reinsurance Held

No definition available.

Name:	slf_ExpenseForPolicyholderClaimsAndBenefitsPaidWithoutReductionForReinsuranceHeld
Namespace Prefix:	slf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Expense For Policyholder Claims And Benefits Paid, Without Reduction For Reinsurance Held, Annuity Payments

No definition available.

Name:	slf_ExpenseForPolicyholderClaimsAndBenefitsPaidWithoutReductionForReinsuranceHeldAnnuityPayments
Namespace Prefix:	slf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Expense For Policyholder Claims And Benefits Paid, Without Reduction For Reinsurance Held, Death And Disability Benefits

No definition available.

Name:	slf_ExpenseForPolicyholderClaimsAndBenefitsPaidWithoutReductionForReinsuranceHeldDeathAndDisabilityBenefits
Namespace Prefix:	slf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Expense For Policyholder Claims And Benefits Paid, Without Reduction For Reinsurance Held, Health Benefits

No definition available.

Name:	slf_ExpenseForPolicyholderClaimsAndBenefitsPaidWithoutReductionForReinsuranceHeldHealthBenefits
Namespace Prefix:	slf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Expense For Policyholder Claims And Benefits Paid, Without Reduction For Reinsurance Held, Maturities And Surrenders

No definition available.

Name:	slf_ExpenseForPolicyholderClaimsAndBenefitsPaidWithoutReductionForReinsuranceHeldMaturitiesAndSurrenders
Namespace Prefix:	slf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Expense For Policyholder Claims And Benefits Paid, Without Reduction For Reinsurance Held, Policyholder Dividends And Interest On Claims And Deposits

No definition available.

Name:	slf_ExpenseForPolicyholderClaimsAndBenefitsPaidWithoutReductionForReinsuranceHeldPolicyholderDividendsAndInterestOnClaimsAndDeposits
Namespace Prefix:	slf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Insurance Contracts [Abstract]

No definition available.

Name:	slf_InsuranceContractsAbstract
Namespace Prefix:	slf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration