Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2014

Fair Value Disclosures [Abstract]

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

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

	Fair Value Measurement at Reporting Date Using
June 30, 2014	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	31,583	$	—	$	—	$	31,583
Total assets	$	31,583	$	—	$	—	$	31,583

	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

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

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, 2014		December 31, 2013		June 30, 2013 As Revised
Cash equivalents	$	31,583	$	89,336	$	144,605
Cash	114,875		139,785		103,228
Total cash and cash equivalents	$	146,458	$	229,121	$	247,833

Fair Value Measurements, Nonrecurring [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 condensed consolidated balance sheets are as follows: 

		June 30, 2014				December 31, 2013				June 30, 2013
(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	$	112,132	$	111,999	$	117,202	$	116,915	$	76,496	$	76,100
Liabilities (including current maturities):
Senior notes payable2	Level 3	$	200,000	$	222,920	$	200,000	$	225,865	$	200,000	$	227,902
Credit Agreement loan2	Level 3	70,000		69,781		70,000		69,601		70,000		69,321

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

²The fair values of the senior notes payable and Credit Agreement (defined in Note 11) loan are based on borrowing rates available to us for long-term loans with similar terms, average maturities, and credit risk.