Fair-Value Measurements

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Fair-Value Measurements

Assets and liabilities reported at fair value are classified in one of the following three levels within the fair-value hierarchy:

Level 1: Quoted market prices in active markets for identical assets or liabilities

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data

Level 3: Unobservable inputs that are not corroborated by market data

Financial Assets Measured at Fair Value on a Recurring Basis

The following table summarizes the valuation of financial instruments within the fair-value hierarchy:

	March 31, 2013
(Dollars in thousands)	Total		Level 1		Level 2		Level 3
Cash equivalents	$	345,784	$	64,592	$	281,192	$	—

	December 31, 2012
(Dollars in thousands)	Total		Level 1		Level 2		Level 3
Cash equivalents	$	378,266	$	70,488	$	307,778	$	—
Current marketable securities	3,200		—		3,200		—

Cash equivalents consist of short-term interest-bearing instruments (primarily commercial paper, certificates of deposit and money-market funds) with maturities of three months or less at the date of purchase. Current marketable securities consist of variable-rate demand notes.

Money-market funds reflect their published net asset value and are classified as Level 1 instruments. Commercial paper, certificates of deposit and variable-rate demand notes are generally valued using published interest rates for instruments with similar terms and maturities, and accordingly, are classified as Level 2 instruments. At March 31, 2013, the weighted-average remaining maturity of the cash equivalents was less than one month. Based on their short maturities, the carrying amount of the cash equivalents approximates their fair value.