Fair Value Measurement (Tables)

12 Months Ended

Dec. 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 consolidated balance sheets on a recurring basis for each of the fair value levels (in thousands):

	Fair Value Measurement at Reporting Date Using
December 31, 2013	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	89,336	$	—	$	—	$	89,336
Total assets	$	89,336	$	—	$	—	$	89,336

December 31, 2012	Fair Value Measurement at Reporting Date Using
	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

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):

December 31,	2013		2012
Cash equivalents	$	89,336	$	206,542
Cash	139,785		115,448
Total cash and cash equivalents	$	229,121	$	321,990

Fair Value, by Balance Sheet Grouping [Table Text Block]

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

December 31,		2013				2012
	Fair Value Hierarchy	Carrying Value		Fair Value		Carrying Value		Fair Value
Assets:
Held-to-maturity marketable securities	Level 1	$	117,202	$	116,915	$	111,430	$	111,525
Liabilities (including current maturities):
Senior notes payable1	Level 3	$	200,000	$	225,865	$	208,333	$	243,118
Credit Agreement loan1	Level 3	70,000		69,601		70,000		70,444

¹The fair values of the senior notes payable and Credit Agreement (as defined under “Credit Agreement” in Note 12) loan are based on borrowing rates available to us for long-term loans with similar terms, average maturities, and credit risk.