Investments

Certificates of Deposit – We held $12.7 million and $5.2 million in certificates of deposit at September 30, 2013, and December 31, 2012, respectively. At September 30, 2013, the certificates of deposit bear interest ranging from 0.10% to 0.90% per annum and have various maturities ranging from approximately two months to 18 months.

Investments Held to Maturity – Our investments held to maturity are comprised of $29.3 million of corporate notes and bonds with original maturities ranging from less than one month to approximately 18 months. The investments have moderate risk with S&P ratings ranging from A+ 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 September 30, 2013 and December 31, 2012:



	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Loss)			Fair Value
September 30, 2013:	(in thousands)
Current assets:
Investments held to maturity	$	11,421	$	3	$	—		$	11,424
Non current assets:
Investments held to maturity	17,867		—		(20		)	17,847
Total	$	29,288	$	3	$	(20	)	$	29,271
December 31, 2012:
Current assets:
Investments held to maturity	$	2,832	$	—	$	(1	)	$	2,831
Non current assets:
Investments held to maturity	8,041		—		(9		)	8,032
Total	$	10,873	$	—	$	(10	)	$	10,863