Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following tables summarize assets and liabilities measured at fair value in the condensed consolidated balance sheets on a recurring basis for each of the fair value levels:

June 30, 2013	Fair Value Measurement at Reporting Date Using
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	144,605	$	—	$	—	$	144,605
Total assets	$	144,605	$	—	$	—	$	144,605

December 31, 2012	Fair Value Measurement at Reporting Date Using
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	201,542	$	—	$	—	$	201,542
Held-to-maturity commercial paper	5,000		—		—		5,000
Total assets	$	206,542	$	—	$	—	$	206,542

June 30, 2012	Fair Value Measurement at Reporting Date Using
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	167,427	$	—	$	—	$	167,427
Held-to-maturity commercial paper	4,997		—		—		4,997
Total assets	$	172,424	$	—	$	—	$	172,424

Schedule of Cash and Cash Equivalents [Table Text Block]

A reconciliation of cash equivalents to consolidated cash and cash equivalents is as follows:

(in thousands)	June 30, 2013		December 31, 2012		June 30, 2012
Cash equivalents	$	144,605	$	206,542	$	172,424
Cash	103,228		115,448		65,527
Total cash and cash equivalents	$	247,833	$	321,990	$	237,951

Fair Value Measurements, Nonrecurring [Table Text Block]

The carrying values and estimated fair values of our financial instruments that are not required to be measured at fair value in the condensed consolidated balance sheets are as follows: 

		June 30, 2013				December 31, 2012				June 30, 2012
(in thousands)	Fair Value Hierarchy	Carrying Value		Fair Value		Carrying Value		Fair Value		Carrying Value		Fair Value
Assets:
Held-to-maturity marketable securities1	Level 1	$	76,496	$	76,100	$	111,430	$	111,525	$	89,060	$	89,239
Liabilities (including current maturities):
Senior notes payable2	Level 3	$	200,000	$	227,902	$	208,333	$	243,118	$	208,333	$	239,443
Credit Agreement loan2	Level 3	70,000		69,321		70,000		70,444		—		—

¹Held-to-maturity marketable securities are periodically assessed for other-than-temporary impairment.

²The fair values of the senior notes payable and Credit Agreement loan are based on borrowing rates available to us for long-term loans with similar terms, average maturities, and credit risk.