10. INVESTMENTS

The Company had cash and cash equivalents of $421.5 million and $443.10 million at March 31, 2015 and December 31, 2014, respectively. Cash and cash equivalents generally consist of cash in banks, as well as highly liquid investments in money market funds, time deposits, savings accounts, commercial paper, and corporate debt securities.

The Company’s U.S. government securities are mostly comprised of direct U.S. Treasury obligations that are guaranteed by the U.S. government and U.S. government agency securities are mostly comprised of U.S. government agency instruments, including mortgage-backed securities. The Company’s non-U.S. government securities are mostly comprised of non-U.S. government instruments, mainly municipal and foreign government securities. To ensure that the investment portfolio is sufficiently diversified, the Company’s investment policy requires that a certain percentage of the Company’s portfolio be invested in these types of securities.

The Company’s corporate debt securities are comprised of publicly-traded domestic and foreign corporate debt securities. The Company does not purchase auction rate securities, and investments are in instruments that meet high quality credit rating standards, as specified in the Company’s investment policy guidelines. These guidelines also limit the amount of credit exposure to any one issuer or type of instrument.

At March 31, 2015, the Company’s long-term investments had contractual maturities of one to two years.

In addition, the Company has short-term and long-term investments in debt securities which are summarized as follows (in thousands):

	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Balances at March 31, 2015:
Investments-Short-term:
U.S. government securities	$	32,183	$	18	$	—		$	32,201
U.S. government agency securities		66,737		12		(5	)		66,744
Non-U.S. government securities		9,556		—		(1	)		9,555
Corporate debt securities		97,602		17		(34	)		97,585
Total investments - short-term	$	206,078	$	47	$	(40	)	$	206,085
Investments-Long-term:
U.S. government securities	$	15,140	$	23	$	—		$	15,163
U.S. government agency securities		14,040		13		—			14,053
Corporate debt securities		11,944		9		(11	)		11,942
Total investments - long-term	$	41,124	$	45	$	(11	)	$	41,158

Balances at December 31, 2014:
Investments-Short-term:
U.S. government securities	$	26,930	$	7	$	(2	)	$	26,935
U.S. government agency securities		59,336		7		(6	)		59,337
Non-U.S. government securities		8,764		2		—			8,766
Corporate debt securities		90,782		10		(47	)		90,745
Total investments - short-term	$	185,812	$	26	$	(55	)	$	185,783
Investments-Long-term:
U.S. government securities	$	25,320	$	4	$	(10	)	$	25,314
U.S. government agency securities		17,369		1		(14	)		17,356
Corporate debt securities		16,540		2		(15	)		16,527
Total investments - long-term	$	59,229	$	7	$	(39	)	$	59,197

Unrealized Losses

The following table summarizes the fair value and gross unrealized losses of the Company’s investments, including investments categorized as cash equivalents, with unrealized losses aggregated by type of investment instrument and length of time that individual securities have been in a continuous unrealized loss position (in thousands):

	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
March 31, 2015:
U.S. government securities	$	2,253	$	—		$	—	$	—		$	2,253	$	—
U.S. government agency securities		27,475		(5	)		—		—			27,475		(5	)
Non-U.S. government securities		7,165		(1	)		—		—			7,165		(1	)
Corporate debt securities		42,926		(44	)		805		(1	)		43,731		(45	)
Total investments	$	79,819	$	(50	)	$	805	$	(1	)	$	80,624	$	(51	)
December 31, 2014:
U.S. government securities	$	22,355	$	(12	)	$	—	$	—		$	22,355	$	(12	)
U.S. government agency securities		27,348		(20	)		—		—			27,348		(20	)
Corporate debt securities		59,667		(62	)		—		—			59,667		(62	)
Total investments	$	109,370	$	(94	)	$	—	$	—		$	109,370	$	(94	)

During the three months ended March 31, 2015 and 2014, there were no investments in the Company’s portfolio that were other-than temporarily impaired and the Company did not incur any material realized net gains or losses.