| For the Year Ended December 31, 2013 | Exelon | Generation | ComEd | PECO | BGE |
| | | | | | | | | | | | | |
| | Plant basis differences | $ | (11,612) | $ | (3,879) | $ | (3,523) | $ | (2,573) | $ | (1,538) |
| | Accrual based contracts | | (214) | | (214) | | — | | — | | — |
| | Derivatives and other financial instruments | | (509) | | (505) | | (4) | | — | | — |
| | Deferred pension and post-retirement obligation | | 1,489 | | (362) | | (522) | | — | | (74) |
| | Nuclear decommissioning activities | | (647) | | (646) | | — | | — | | — |
| | Deferred debt refinancing costs | | 173 | | 79 | | (21) | | (3) | | (5) |
| | Regulatory | | (1,611) | | — | | (241) | | 42 | | (253) |
| | Tax loss carryforward | | 252 | | 76 | | 47 | | 11 | | 52 |
| | Tax credit carryforward | | 534 | | 534 | | — | | — | | — |
| | Investment in CENG | | (541) | | (541) | | — | | — | | — |
| | Other, net | | 804 | | 67 | | 154 | | 122 | | 26 |
| | | | | | | | | | | | | |
| Deferred income tax liabilities (net) | $ | (11,882) | $ | (5,391) | $ | (4,110) | $ | (2,401) | $ | (1,792) |
| Unamortized investment tax credits | | (490) | | (454) | | (22) | | (3) | | (6) |
| | | | | | | | | | | | | |
| Total deferred income tax liabilities (net) and | | | | | | | | | | |
| | unamortized investment tax credits | $ | (12,372) | $ | (5,845) | $ | (4,132) | $ | (2,404) | $ | (1,798) |
| | | | | | | | | | | | | |
| For the Year Ended December 31, 2012 | Exelon | Generation | ComEd | PECO | BGE |
| | | | | | | | | | | | | |
| | Plant basis differences | $ | (10,689) | $ | (3,545) | $ | (3,537) | $ | (2,437) | $ | (1,553) |
| | Accrual based contracts | | (389) | | (389) | | — | | — | | — |
| | Derivatives and other financial instruments | | (392) | | (479) | | (4) | | — | | — |
| | Deferred pension and post-retirement obligation | | 2,356 | | (439) | | (598) | | (11) | | (12) |
| | Nuclear decommissioning activities | | (604) | | (604) | | — | | — | | — |
| | Deferred debt refinancing costs | | (537) | | 163 | | (25) | | (4) | | (4) |
| | Regulatory | | (1,857) | | — | | (116) | | 50 | | (253) |
| | Tax loss carryforward | | 421 | | 226 | | 32 | | 14 | | 105 |
| | Tax credit carryforward | | 226 | | 226 | | — | | — | | — |
| | Investment in CENG | | (405) | | (419) | | — | | — | | — |
| | Other, net | | 701 | | 9 | | 83 | | 100 | | 67 |
| | | | | | | | | | | | | |
| Deferred income tax liabilities (net) | $ | (11,169) | $ | (5,251) | $ | (4,165) | $ | (2,288) | $ | (1,650) |
| Unamortized investment tax credits | | (251) | | (216) | | (24) | | (3) | | (6) |
| | | | | | | | | | | | | |
| Total deferred income tax liabilities (net) and | | | | | | | | | | |
| | unamortized investment tax credits | $ | (11,420) | $ | (5,467) | $ | (4,189) | $ | (2,291) | $ | (1,656) |
