Trade receivables are presented net of allowances for contractual discounts and uncompensated care. The Company determines its allowances for contractual discounts and uncompensated care based on estimated payer mix, payer reimbursement schedules, and historical collection experience. The allowances are reviewed monthly and adjusted periodically based on actual collections. Billings are charged off against the uncompensated care allowance when it is probable that the receivable will not be recovered. The allowance for contractual discounts is related primarily to Medicare and Medicaid patients. The allowance for uncompensated care is related primarily to receivables recorded for self-pay patients.

The Company has not changed its discount policies related to self-pay patients or deductible and copayment balances for insured patients during either 2014 or 2013. The allowance for uncompensated care was 37.7% of receivables from non-governmental payers as of March 31, 2014, compared to 39.2% at December 31, 2013, and 42.4% at March 31, 2013. Receivables from private insurance providers accounted for 63% of receivables from non-governmental payers as of March 31, 2014, compared to 60% as of December 31, 2013, and 59% as of March 31, 2013. The remainder of receivables from non-governmental payers are attributable to self-pay patients.

The Company recognizes patient transport revenue at its standard rates for services provided, regardless of expected payer. In the period that services are provided and based upon historical experience, the Company records a significant provision for uncompensated care related to uninsured patients who will be unable or unwilling to pay for the services provided and a provision for contractual discounts related to Medicare and Medicaid transports. Air medical services contract revenue consists of monthly fees and hourly flight fees billed to hospitals or other institutions under exclusive operating agreements. These fees are earned regardless of when, or if, the institution is reimbursed for these services by its patients, their insurers, or the federal government. As a result, the Company does not maintain an allowance or provision for uncompensated care for air medical services contract revenue and related receivables.

Patient transport revenue, net of provision for contractual discounts but before provision for uncompensated care, by major payer class, was as follows (amounts in thousands) for the quarters ended March 31: