The following table presents a reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses: | | | | | | | | | | | | Three Months Ended
March 31, | (in millions) | | 2020 | | 2019 | Claims and claim adjustment expense reserves at beginning of year | | $ | 51,836 |
| | $ | 50,653 |
| Less reinsurance recoverables on unpaid losses | | 8,035 |
| | 8,182 |
| Cumulative effect of adoption of updated accounting guidance for credit losses at January 1, 2020 | | 53 |
| | — |
| Net reserves at beginning of year | | 43,854 |
| | 42,471 |
| | | | | | Estimated claims and claim adjustment expenses for claims arising in the current year | | 4,763 |
| | 4,435 |
| Estimated decrease in claims and claim adjustment expenses for claims arising in prior years | | (3 | ) | | (16 | ) | Total increases | | 4,760 |
| | 4,419 |
| | | | | | Claims and claim adjustment expense payments for claims arising in: | | |
| | |
| Current year | | 947 |
| | 970 |
| Prior years | | 3,439 |
| | 3,320 |
| Total payments | | 4,386 |
| | 4,290 |
| Unrealized foreign exchange (gain) loss | | (210 | ) | | 41 |
| Net reserves at end of period | | 44,018 |
| | 42,641 |
| Plus reinsurance recoverables on unpaid losses | | 7,926 |
| | 8,063 |
| Claims and claim adjustment expense reserves at end of period | | $ | 51,944 |
| | $ | 50,704 |
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