Deferred income taxes are provided for temporary differences between the financial reporting and the tax basis of assets and liabilities. The deferred tax assets (liabilities) resulting from these differences were as follows (in thousands):
Self-insurance retention accruals
Bad debt reserves
Excess of tax over book depreciation and amortization
Net deferred tax assets
Total deferred tax assets were $103.4 million and $99.3 million, and total deferred tax liabilities were $34.5 million and $64.6 million on December 30, 2016 and December 25, 2015. The difference between the deferred income tax provision and the change in net deferred income taxes is due to the change in other comprehensive income (loss) items and the impact of acquisitions.
The Company files income tax returns in the U.S. federal jurisdiction, and various states and foreign jurisdictions. With few exceptions, the Company is no longer subject to U.S. federal, state and local, or non-U.S. income tax examinations by tax authorities for years before 2010.
The Company records penalties and accrued interest related to uncertain tax positions in income tax expense. Total reserves for uncertain tax positions were not material.
A summary of debt follows (dollars in thousands):
Average Interest Rate
December 30, 2016
Private placement unsecured fixed-rate notes
Unsecured revolving credit facility
Notes payable to banks
Total debt, including current portion
The estimated fair value of the fixed interest rate private placement debt was $325 million on December 30, 2016 and $320 million on December 25, 2015. The fair value of variable rate borrowings approximates carrying value. The Company uses significant other observable inputs to estimate fair value (level 2 of the fair value hierarchy) based on the present value of future cash flows and rates that would be available for issuance of debt with similar terms and remaining maturities.
On December 15, 2016, the Company executed an amendment to its revolving credit agreement, extending the expiration date to December 15, 2021 and decreasing certain interest rates and fees. The amended agreement with a syndicate of lenders provides up to $500 million of committed credit, available for general corporate purposes, working capital needs, share repurchases and acquisitions. The Company may borrow up to $50 million under the swingline portion of the facility for daily working capital needs.