Investments (Tables)

6 Months Ended

Jun. 30, 2017

Investments [Abstract]

Summary of Investments

The following is a summary of our investments at June 30, 2017 (in thousands):

				Gross Unrealized
	Cost			Gains			Losses				Estimated Fair Value
Available-for-sale securities (1):
Corporate debt securities		$	40,250		$	—		$	(25	)		$	40,225
Other municipal debt securities			3,000			—			(2	)			2,998
Total available-for-sale securities		$	43,250		$	—		$	(27	)		$	43,223

(1) Our available-for-sale securities are held at amortized cost.

Temporarily Impaired Investments

Investments we consider to be temporarily impaired at June 30, 2017 were as follows (in thousands):

			Less than 12 Months of Temporary Impairment							More than 12 Months of Temporary Impairment						Total Temporary Impairment
	Number of Investments		Estimated Fair Value			Unrealized Losses				Estimated Fair Value			Unrealized Losses			Estimated Fair Value			Unrealized Losses
Corporate debt securities		17		$	31,437		$	(25	)		$	—		$	—		$	31,437		$	(25	)
Other municipal debt securities		1			2,998			(2	)			—			—			2,998			(2	)
Total temporarily impaired securities		18		$	34,435		$	(27	)		$	—		$	—		$	34,435		$	(27	)