Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value Disclosures [Abstract]

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

The following tables summarize each class of assets and liabilities measured at fair value on a recurring basis as well as assets and liabilities that are disclosed but not recorded at fair value: 

September 30, 2012	Fair Value Measurement at Reporting Date Using
(in thousands)	Level 11		Level 22		Level 33		Total
Cash equivalents
Money market funds	$	185,586	$	—	$	—	$	185,586
Held-to-maturity commercial paper	14,495		—		—		14,495
Marketable securities
Held-to-maturity marketable securities	85,133		—		—		85,133
Total assets	$	285,214	$	—	$	—	$	285,214
Long-term debt (including current maturities)
Senior notes payable	$	—	$	—	$	243,219	$	243,219
Total liabilities	$	—	$	—	$	243,219	$	243,219

December 31, 2011	Fair Value Measurement at Reporting Date Using
(in thousands)	Level 11		Level 22		Level 33		Total
Cash equivalents
Money market funds	$	178,174	$	—	$	—	$	178,174
Held-to-maturity commercial paper	4,999		—		—		4,999
Marketable securities
Held-to-maturity marketable securities	149,979		—		—		149,979
Total assets	$	333,152	$	—	$	—	$	333,152
Long-term debt (including current maturities)
Senior notes payable	$	—	$	—	$	250,541	$	250,541
Total liabilities	$	—	$	—	$	250,541	$	250,541

September 30, 2011	Fair Value Measurement at Reporting Date Using
(in thousands)	Level 11		Level 22		Level 33		Total
Cash equivalents
Money market funds	$	149,966	$	—	$	—	$	149,966
Held-to-maturity commercial paper	4,997		—		—		4,997
Marketable securities
Held-to-maturity marketable securities	137,194		—		—		137,194
Total assets	$	292,157	$	—	$	—	$	292,157
Long-term debt (including current maturities)
Senior notes payable	$	—	$	—	$	242,698	$	242,698
Total liabilities	$	—	$	—	$	242,698	$	242,698

¹Quoted prices in active markets for identical assets or liabilities.

²Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

³Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Schedule of Cash and Cash Equivalents [Table Text Block]

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

(in thousands)	September 30, 2012		December 31, 2011		September 30, 2011
Money market funds	$	185,586	$	178,174	$	149,966
Held-to-maturity commercial paper	14,495		4,999		4,997
Cash	87,241		73,817		38,136
Total cash and cash equivalents	$	287,322	$	256,990	$	193,099