(5) Receivables

The components of receivables were as follows (in thousands):

	June 30,		December 31,
	2013		2012
Billed	$	48,294	$	59,496
Unbilled		512,650		439,726
Total	$	560,944	$	499,222

Under the terms of the company's Commercial Resupply Services ("CRS") contract with the National Aeronautics and Space Administration ("NASA"), approximately 25% of the contract value is billable to the customer and collectible only upon the completion of launch and delivery milestones for each of eight CRS contract missions. Unbilled receivables at June 30, 2013 and December 31, 2012 included $343 million and $277 million, respectively, pertaining to the CRS contract. Since the commencement of the CRS contract through June 30, 2013, a total of approximately $1.1 billion of revenues have been recognized on the contract, which has a total contract value of approximately $1.9 billion.

As of June 30, 2013 and December 31, 2012, unbilled receivables also included $8.3 million and $8.7 million, respectively, of incentive fees on certain completed satellite contracts that become due incrementally over periods of up to 15 years, subject to the achievement of performance criteria.

In addition, certain satellite contracts require the company to refund cash to the customer if performance criteria, which cover periods of up to 15 years, are not satisfied. As of June 30, 2013, the company could be required to refund up to $19.7 million to customers if certain completed satellites were to fail to satisfy performance criteria. Orbital generally procures insurance policies under which the company believes it would recover satellite incentive fees that are not earned and performance refund obligations.