Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2015

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
March 31, 2015	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	54,709	$	—	$	—	$	54,709
Total assets	$	54,709	$	—	$	—	$	54,709

	Fair Value Measurement at Reporting Date Using
December 31, 2014	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	60,618	$	—	$	—	$	60,618
Total assets	$	60,618	$	—	$	—	$	60,618

	Fair Value Measurement at Reporting Date Using
March 31, 2014	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	49,770	$	—	$	—	$	49,770
Total assets	$	49,770	$	—	$	—	$	49,770

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, 2015		December 31, 2014		March 31, 2014
Cash equivalents	$	54,709	$	60,618	$	49,770
Cash	184,694		195,343		156,010
Total cash and cash equivalents	$	239,403	$	255,961	$	205,780

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: 

		March 31, 2015				December 31, 2014				March 31, 2014
(in thousands)	Fair Value Hierarchy	Carrying Value		Fair Value		Carrying Value		Fair Value		Carrying Value		Fair Value
Assets:
Held-to-maturity marketable securities	Level 1	$	99,804	$	99,811	$	102,067	$	101,808	$	107,112	$	106,864
Liabilities (including current maturities):
Senior notes payable1	Level 3	$	200,000	$	222,973	$	200,000	$	220,226	$	200,000	$	226,503
Credit Agreement loan1	Level 3	70,000		70,391		70,000		70,153		70,000		69,368

¹The 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.