Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 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:

March 31, 2013	Fair Value Measurement at Reporting Date Using
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	160,845	$	—	$	—	$	160,845
Held-to-maturity commercial paper	4,999		—		—		4,999
Total assets	$	165,844	$	—	$	—	$	165,844

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

March 31, 2012	Fair Value Measurement at Reporting Date Using
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	157,034	$	—	$	—	$	157,034
Held-to-maturity commercial paper	4,997		—		—		4,997
Total assets	$	162,031	$	—	$	—	$	162,031

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)	March 31, 2013		December 31, 2012		March 31, 2012
Cash equivalents	$	165,844	$	206,542	$	162,031
Cash	94,929		115,448		64,195
Total cash and cash equivalents	$	260,773	$	321,990	$	226,226

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: 

		March 31, 2013				December 31, 2012				March 31, 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	$	102,799	$	102,872	$	111,430	$	111,525	$	140,558	$	140,728
Liabilities (including current maturities):
Senior notes payable2	Level 3	$	208,333	$	242,071	$	208,333	$	243,118	$	216,667	$	246,600
Credit Agreement loan2	Level 3	70,000		70,568		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 required to be disclosed only, and were based on borrowing rates available to us for long-term loans with similar terms, average maturities, and credit risk.