Available-for-Sale Securities and Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2017

Available-for-Sale Securities and Fair Value Measurements

Schedule of amortized cost and estimated fair values for available-for-sale securities

	June 30, 2017
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. government agencies	$	9,989	$	—	$	—	$	9,989
U.S. commercial paper	68,365		—		—		68,365
Money market funds	51,906		—		—		51,906
Total	$	130,260	$	—	$	—	$	130,260

	December 31, 2016
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. government agencies	$	12,428	$	1	$	—	$	12,429
U.S. commercial paper	72,065		—		—		72,065
Money market funds	64,319		—		—		64,319
Total	$	148,812	$	1	$	—	$	148,813

Schedule of estimated fair values by hierarchy

	Estimated Fair Value Measurements as of June 30, 2017 Using:
Types of Instruments	Quoted Price in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
U.S. government agencies	$	—	$	9,989	$	—	$	9,989
U.S. commercial paper	—		68,365		—		68,365
Money market funds	51,906		—		—		51,906
Total assets measured at estimated fair value	$	51,906	$	78,354	$	—	$	130,260
Liabilities
2023 Notes	$	—	$	220,356	$	—	$	220,356
Non-recourse notes due 2029 (the “2029 Notes”)	—		430,156		—		430,156
Total fair value of liabilities	$	—	$	650,512	$	—	$	650,512

	Estimated Fair Value Measurements as of December 31, 2016 Using:
Types of Instruments	Quoted Price in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
U.S. government agencies	$	—	$	12,429	$	—	$	12,429
U.S. commercial paper	—		72,065		—		72,065
Money market funds	64,319		—		—		64,319
Total assets measured at estimated fair value	$	64,319	$	84,494	$	—	$	148,813
Liabilities
2023 Notes	$	—	$	202,125	$	—	$	202,125
2029 Notes	—		487,189		—		487,189
Total fair value of liabilities	$	—	$	689,314	$	—	$	689,314