Our accounts and notes receivable are recorded at cost. The portion of our notes receivable due in one year or less are included in accounts and notes receivable and the long-term portion is included in other assets, net. Lease receivables arise from sales-type leases of products. We typically sell, without recourse, the contractual right to the lease payment stream and assets under lease to third parties. For certain customers, we retain the lease.

The contractual amounts due under the leases we retained as of March 31, 2012 were as follows (table in thousands):

Year	Contractual Amounts Due Under Leases
Due within one year	$	112,125
Due within two years		87,656
Due within three years		78,307
Thereafter		899
Total		278,987
Less amounts representing interest		(6,156)
Present value		272,831
Current portion (included in accounts and notes receivable)		109,604
Long-term portion (included in other assets, net)	$	163,227

Subsequent to March 31, 2012, we sold $42.6 million of these notes to third parties without recourse.

We maintain an allowance for credit losses on our accounts and notes receivable. The allowance is based on the credit worthiness of our customers, including an assessment of the customer's financial position, operating performance and their ability to meet their contractual obligation. We assess the credit scores for our customers each quarter. In addition, we consider our historical experience, the age of the receivable and current market and economic conditions. Uncollectible amounts are charged against the allowance account.

In the event we determine that a lease may not be paid, we include in our allowance an amount for the outstanding balance related to the lease receivable. As of March 31, 2012, amounts from lease receivables past due for more than 90 days were not significant.

The following table presents the activity of our allowance for credit losses related to lease receivables for the three months ended March 31, 2012 and 2011 (table in thousands):

	March 31,		March 31,
	2012		2011
Balance, beginning of the period	$	24,247	$	44,661
Recoveries		(11,758)		(14,332)
Provisions		8,559		16,313
Balance, end of the period	$	21,048	$	46,642

Gross lease receivables totaled $279.0 million and $277.7 million as of March 31, 2012 and 2011, respectively, before the allowance. The components of these balances were individually evaluated for impairment.