Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

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
September 30, 2018	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	68,765	$	—	$	—	$	68,765
Other noncurrent assets
Restricted cash		5,599		—		—		5,599
Total assets	$	74,364	$	—	$	—	$	74,364
December 31, 2017
Cash equivalents
Money market funds	$	37,284	$	—	$	—	$	37,284
Commercial paper		9,967		—		—		9,967
Total assets	$	47,251	$	—	$	—	$	47,251
September 30, 2017
Cash equivalents
Money market funds	$	22,896	$	—	$	—	$	22,896
Total assets	$	22,896	$	—	$	—	$	22,896

Schedule of Carrying and Fair Value Amounts

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 were as follows:

		September 30, 2018				December 31, 2017				September 30, 2017
(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	$	81,103	$	79,941	$	132,790	$	132,002	$	117,805	$	117,349
Liabilities (including current maturities):
2019 Notes1	Level 3	$	80,000	$	82,191	$	80,000	$	82,190	$	120,000	$	124,792
Credit Agreement - term loan1	Level 3		148,125		148,832		90,000		89,871		91,250		91,078
Credit Agreement - revolving credit facility1	Level 3		137,000		137,636		55,000		55,054		30,000		30,018
Convertible notes1	Level 1		69,659		69,472		—		—		—		—

¹See Note 14 for definitions of, and more information about, the 2019 Notes, Credit Agreement and Convertible notes.