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

6 Months Ended

Jun. 30, 2016

Available-for-Sale Securities and Fair Value Measurements

Schedule of available-for-sale securities

(In thousands)	June 30, 2016		December 31, 2015
Cash and cash equivalents	$	110,228	$	148,673
Short-term marketable securities	40,921		28,103
Total	$	151,149	$	176,776

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

	June 30, 2016
(In thousands)	Amortized Cost		Gross Unrealized Gains		Estimated Fair Value
U.S. government agencies	$	19,970	$	6	$	19,976
U.S. commercial paper	52,535		—		52,535
Money market funds	78,638		—		78,638
Total	$	151,143	$	6	$	151,149

	December 31, 2015
(In thousands)	Amortized Cost		Gross Unrealized Losses			Estimated Fair Value
U.S. government agencies	$	14,406	$	(1	)	$	14,405
U.S. corporate notes	2,702		(1		)	2,701
U.S. commercial paper	10,997		—			10,997
Money market funds	148,673		—			148,673
Total	$	176,778	$	(2	)	$	176,776

Schedule of estimated fair values

	Estimated Fair Value Measurements as of June 30, 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	$	—	$	19,976	$	—	$	19,976
U.S. commercial paper	—		52,535		—		52,535
Money market funds	78,638		—		—		78,638
Total assets measured at estimated fair value	$	78,638	$	72,511	$	—	$	151,149
Liabilities
Convertible subordinated notes due 2023	$	—	$	197,825	$	—	$	197,825
Non-recourse notes due 2029	—		494,017		—		494,017
Total fair value of liabilities	$	—	$	691,842	$	—	$	691,842

	Estimated Fair Value Measurements as of December 31, 2015 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	$	—	$	14,405	$	—	$	14,405
U.S. corporate notes	—		2,701		—		2,701
U.S. commercial paper	—		10,997		—		10,997
Money market funds	148,673		—		—		148,673
Total assets measured at estimated fair value	$	148,673	$	28,103	$	—	$	176,776
Liabilities
Convertible subordinated notes due 2023	$	—	$	189,100	$	—	$	189,100
Non-recourse notes due 2029	—		470,970		—		470,970
Total fair value of liabilities	$	—	$	660,070	$	—	$	660,070