Gross Premiums. DAC associated with term life policies is primarily amortized in proportion to gross premiums.
For most long duration contracts, we utilize best estimate assumptions as of the date the policy is issued or acquired with provisions for the risk of adverse deviation, as appropriate. After the liabilities are initially established, we perform premium deficiency tests using best estimate assumptions as of the testing date without provisions for adverse deviation. If the liabilities determined based on these best estimate assumptions are greater than the net reserves (i.e., U.S. GAAP reserves net of any DAC or DSI asset), the existing net reserves are adjusted by first reducing these assets by the amount of the deficiency or to zero through a charge to current period earnings. If the deficiency is more than these asset balances for insurance contracts, we then increase the net reserves by the excess, again through a charge to current period earnings. If a premium deficiency is recognized, the assumptions as of the premium deficiency test date are locked in and used in subsequent valuations and the net reserves continue to be subject to premium deficiency testing.
Total liabilities increased $8.9 billion, from $144.3 billion at December 31, 2015 to $153.2 billion at December 31, 2016. Significant components were:
Prudential Financial employs a Capital Protection Framework (the "Framework”) to ensure that sufficient capital resources are available to maintain adequate capitalization and competitive RBC ratios and solvency margins under various stress scenarios. The Framework incorporates the potential impacts from market related stresses, including equity markets, real estate, interest rates, and credit losses. The Framework addresses the potential capital consequences, under stress scenarios, of certain of these net risks and the strategies we use to mitigate them, including equity market exposure affecting the statutory capital of the Company and Prudential Financial as a whole, which is managed through Prudential Financial's equity hedge program and on-balance sheet and contingent sources of capital.
The principal sources of the Company’s liquidity are premiums and certain annuity considerations, investment and fee income, investment maturities and sales as well as internal borrowings. The principal uses of that liquidity include benefits, claims, and payments to policyholders and contractholders in connection with surrenders, withdrawals and net policy loan activity. Other uses of liquidity include commissions, general and administrative expenses, purchases of investments, the payment of dividends to the parent company, hedging activity and payments in connection with financing activities.
Regulation XXX and Guideline AXXX require domestic life insurers to establish statutory reserves for term and universal life insurance policies with long-term premium guarantees that are consistent with the statutory reserves required for other individual life policies with similar guarantees. Many market participants believe that these levels of reserves are excessive relative to the levels reasonably required to maintain solvency for moderately adverse experience. The difference between the statutory reserve