Financial Instruments and Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of Financial Instruments Measured at Fair Value on a Recurring Basis

The financial instruments measured at fair value on a recurring basis at March 31, 2016 were as follows:

	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	20,308	$	—	$	—	$	20,308
Commercial paper	158,973		—		—		158,973
Debt securities:
U.S. Treasury securities	184,949		—		—		184,949
Corporate debt securities	—		8,440		—		8,440
Preferred stock	—		148		—		148
Restricted investments:
Money market fund	5,651		—		—		5,651
	$	369,881	$	8,588	$	—	$	378,469

The financial instruments measured at fair value on a recurring basis at December 31, 2015 were as follows:

	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	18,233	$	—	$	—	$	18,233
Commercial paper	174,973		—		—		174,973
Debt securities:
U.S. Treasury securities	184,740		—		—		184,740
Corporate debt securities	—		6,292		—		6,292
Preferred stock	—		208		—		208
Restricted investments:
Guaranteed income fund	—		7,072		—		7,072
	$	377,946	$	13,572	$	—	$	391,518

Carrying Amount and Fair Value of Financial Instruments

The carrying amount and fair value of the Company’s financial instruments were as follows:

	March 31, 2016					December 31, 2015
	Carrying  value		Fair value		Level	Carrying  value		Fair value		Level
Assets
Retained interest investments	$	10,316	$	13,257	3	$	10,246	$	13,333	3
Investments held by special purpose entities:
Time deposit	$	200,000	$	200,000	3	$	200,000	$	200,000	3
U.S. Treasury securities and cash equivalents	$	8,414	$	8,952	1	$	8,785	$	9,033	1
Liabilities
Senior Notes held by special purpose entity	$	176,147	$	208,525	3	$	176,094	$	178,035	3