Investments and Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2012

Fair Value Disclosures [Abstract]

Schedule of Investments

We monitor the concentration, diversification, maturity, and liquidity of our investment portfolio, which is primarily invested in fixed-income securities, and classify our investment portfolio as shown below:

	As of March 31		As of December 31
($000)	2012		2011
Available-for-sale	$	255,195	$	247,917
Held-to-maturity	17,023		16,347
Trading securities	6,080		5,491
Total	$	278,298	$	269,755

Unrealized Gain (Loss) on Investments

The following table shows the cost, unrealized gains (losses), and fair values related to investments classified as available-for-sale and held-to-maturity:

	As of March 31, 2012									As of December 31, 2011
($000)	Cost		Unrealized Gain		Unrealized Loss			Fair Value		Cost		Unrealized Gain		Unrealized Loss			Fair Value
Available-for-sale:
Government obligations	$	116,672	$	69	$	(430	)	$	116,311	$	139,099	$	72	$	(402	)	$	138,769
Corporate bonds	91,259		62		(241		)	91,080		61,589		14		(280		)	61,323
Commercial paper	28,117		6		(6		)	28,117		29,964		2		(7		)	29,959
Equity securities and exchange-traded funds	8,839		808		(221		)	9,426		8,461		368		(558		)	8,271
Mutual funds	9,304		988		(31		)	10,261		9,298		363		(66		)	9,595
Total	$	254,191	$	1,933	$	(929	)	255,195		$	248,411	$	819	$	(1,313	)	$	247,917
Held-to-maturity:
Certificates of deposit	$	17,023	$	—	$	—		$	17,023	$	16,347	$	—	$	—		$	16,347

Investments Classified by Contractual Maturity Date

The expected maturities of certain fixed-income securities may differ from their contractual maturities because some of these holdings have call features that allow the issuers the right to prepay obligations without penalties.

	As of March 31, 2012				As of December 31, 2011
($000)	Cost		Fair Value		Cost		Fair Value
Available-for-sale:
Due in one year or less	$	166,640	$	166,276	$	155,651	$	155,247
Due in one to two years	69,408		69,232		75,001		74,804
Equity securities, exchange-traded funds, and mutual funds	18,143		19,687		17,759		17,866
Total	$	254,191	$	255,195	$	248,411	$	247,917
Held-to-maturity:
Due in one year or less	$	17,018	$	17,018	$	16,342	$	16,342
Due in one to three years	5		5		5		5
Total	$	17,023	$	17,023	$	16,347	$	16,347

Schedule of Realized Gain (Loss) on Available-For-Sale Securities

The following table shows the realized gains and losses arising from sales of our investments classified as available-for-sale recorded in our Condensed Consolidated Statements of Income: 

	Three months ended March 31
($000)	2012			2011
Realized gains	$	212		$	64
Realized losses	(298		)	—
Realized gains (losses), net	$	(86	)	$	64

Unrealized Gain (Loss) On Trading Securities

The following table shows the net unrealized gains on trading securities as recorded in our Condensed Consolidated Statements of Income:

	Three months ended March 31
($000)	2012		2011
Unrealized gains, net	$	428	$	45

Fair Value, Assets Measured on Recurring Basis

The fair value of our assets subject to fair value measurements and that are measured at fair value on a recurring basis using the fair value hierarchy and the necessary disclosures under FASB ASC 820, Fair Value Measurement, are as follows:

	Fair Value		Fair Value Measurements as of March 31, 2012
	as of		Using Fair Value Hierarchy
($000)	March 31, 2012		Level 1		Level 2		Level 3
Available-for-sale investments
Government obligations	$	116,311	$	—	$	116,311	$	—
Corporate bonds	91,080		—		91,080		—
Commercial paper	28,117		—		28,117		—
Equity securities and exchange-traded funds	9,426		9,426		—		—
Mutual funds	10,261		10,261		—		—
Trading securities	6,080		6,080		—		—
Cash equivalents	14,979		14,979		—		—
Total	$	276,254	$	40,746	$	235,508	$	—

	Fair Value		Fair Value Measurements as of December 31, 2011
	as of		Using Fair Value Hierarchy
($000)	December 31, 2011		Level 1		Level 2		Level 3
Available-for-sale investments
Government obligations	$	138,769	$	—	$	138,769	$	—
Corporate bonds	61,323		—		61,323		—
Commercial paper	29,959		—		29,959		—
Equity securities and exchange-traded funds	8,271		8,271		—		—
Mutual funds	9,595		9,595		—		—
Trading securities	5,491		5,491		—		—
Cash equivalents	30,818		30,818		—		—
Total	$	284,226	$	54,175	$	230,051	$	—