Investments

Certificates of Deposit – We held $6.7 million and $11.4 million in certificates of deposit at June 30, 2015 and December 31, 2014, respectively. At June 30, 2015, the certificates of deposit bear interest ranging from 0.35% to 0.60% per annum and have various maturities ranging from less than six months to approximately 13 months.

Investments Held to Maturity – Our investments held to maturity are comprised of $6.2 million of corporate notes and bonds with original maturities ranging from less than three months to approximately 13 months. The investments have moderate risk with S&P ratings ranging from AA- to BBB-.

We record the amortized cost basis and accrued interest of the corporate notes and bonds in the Consolidated Balance Sheets. We record the interest and amortization of bond premium to interest income in the Consolidated Statements of Income.

The following summarizes the amortized cost and estimated fair value of our investments held to maturity as of

June 30, 2015 and December 31, 2014:



	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Loss)			Fair Value
June 30, 2015:	(in thousands)
Current assets:
Investments held to maturity	$	6,101	$	—	$	(9	)	$	6,092
Non current assets:
Investments held to maturity	75		—		—			75
Total	$	6,176	$	—	$	(9	)	$	6,167
December 31, 2014:
Current assets:
Investments held to maturity	$	11,972	$	—	$	(7	)	$	11,965
Non current assets:
Investments held to maturity	4,015		—		(16		)	3,999
Total	$	15,987	$	—	$	(23	)	$	15,964