Financial Instruments and Fair Value Measurements (Tables)

12 Months Ended

Dec. 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 December 31, 2016 were as follows:

	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	86,236	$	—	$	—	$	86,236
Commercial paper	129,671		—		—		129,671
	215,907		—		—		215,907
Investments:
Corporate debt securities	57,788		81,344		—		139,132
Preferred stock	19,177		17,416		—		36,593
	76,965		98,760		—		175,725
Restricted investments:
Short-term bond	4,226		—		—		4,226
Money market fund	1,410		—		—		1,410
	5,636		—		—		5,636
	$	298,508	$	98,760	$	—	$	397,268

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
	193,206		—		—		193,206
Investments:
U.S. treasury securities	184,740		—		—		184,740
Corporate debt securities	—		6,292		—		6,292
Preferred stock	—		208		—		208
	184,740		6,500		—		191,240
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:

	December 31, 2016					December 31, 2015
	Carrying  value		Fair value		Level	Carrying  value		Fair value		Level
Assets
Retained interest investments	$	10,635	$	13,669	3	$	10,246	$	13,333	3
Investments held by SPEs:
Time deposit	$	200,000	$	200,000	3	$	200,000	$	200,000	3
U.S. Treasury securities and cash equivalents	$	8,590	$	8,398	1	$	8,785	$	9,033	1
Liabilities
Senior Notes held by SPE	$	176,310	$	199,691	3	$	176,094	$	178,035	3