Short-term and Long-term Investments, Restricted Deposits

Short-term and long-term investments and restricted deposits by investment type consist of the following:



	September 30, 2014									December 31, 2013
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	329,439	$	246	$	(4,273	)	$	325,412	$	246,085	$	245	$	(7,494	)	$	238,836
Corporate securities	489,304		2,815		(990		)	491,129		293,912		2,782		(608		)	296,086
Restricted certificates of deposit	5,892		—		—			5,892		5,891		—		—			5,891
Restricted cash equivalents	78,995		—		—			78,995		26,642		—		—			26,642
Municipal securities:
General obligation	49,467		422		(14		)	49,875		54,003		555		(136		)	54,422
Pre-refunded	4,955		46		(16		)	4,985		10,835		82		—			10,917
Revenue	100,312		768		(58		)	101,022		68,801		545		(292		)	69,054
Variable rate demand notes	11,700		—		—			11,700		28,575		—		—			28,575
Asset backed securities	185,270		389		(143		)	185,516		138,803		579		(332		)	139,050
Mortgage backed securities	46,023		753		—			46,776		33,974		—		(83		)	33,891
Cost and equity method investments	58,051		—		—			58,051		22,239		—		—			22,239
Life insurance contracts	15,628		—		—			15,628		15,369		—		—			15,369
Total	$	1,375,036	$	5,439	$	(5,494	)	$	1,374,981	$	945,129	$	4,788	$	(8,945	)	$	940,972

The Company’s investments are classified as available-for-sale with the exception of life insurance contracts and certain cost and equity method investments. The Company’s investment policies are designed to provide liquidity, preserve capital and maximize total return on invested assets with the focus on high credit quality securities. The Company limits the size of investment in any single issuer other than U.S. treasury securities and obligations of U.S. government corporations and agencies. The Company's mortgage backed securities are issued by the Federal National Mortgage Association and carry guarantees by the U.S. government. As of September 30, 2014, 48% of the Company’s investments in securities recorded at fair value that carry a rating by S&P or Moody’s were rated AAA/Aaa, 60% were rated AA-/Aa3 or higher, and 90% were rated A-/A3 or higher. At September 30, 2014, the Company held certificates of deposit, life insurance contracts and cost and equity method investments which did not carry a credit rating.

The fair value of available-for-sale investments with gross unrealized losses by investment type and length of time that individual securities have been in a continuous unrealized loss position were as follows:



	September 30, 2014										December 31, 2013
	Less Than 12 Months					12 Months or More					Less Than 12 Months					12 Months or More
	Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	(204	)	$	62,910	$	(4,069	)	$	178,270	$	(6,188	)	$	172,365	$	(1,307	)	$	26,454
Corporate securities	(972		)	195,027		(18		)	983		(400		)	52,725		(207		)	5,020
Municipal securities:
General obligation	—			—		(14		)	3,456		(72		)	3,480		(63		)	2,426
Pre-refunded	(16		)	1,022		—			—		—			—		—			—
Revenue	(24		)	2,356		(34		)	3,395		(292		)	27,789		—			—
Asset backed securities	(62		)	41,911		(81		)	10,046		(333		)	37,689		—			—
Mortgage backed securities	—			—		—			—		(83		)	33,891		—			—
Total	$	(1,278	)	$	303,226	$	(4,216	)	$	196,150	$	(7,368	)	$	327,939	$	(1,577	)	$	33,900

As of September 30, 2014, the gross unrealized losses were generated from 91 positions out of a total of 332 positions. The change in fair value of fixed income securities is a result of movement in interest rates subsequent to the purchase of the security.

For each security in an unrealized loss position, the Company assesses whether it intends to sell the security or if it is more likely than not the Company will be required to sell the security before recovery of the amortized cost basis for reasons such as liquidity, contractual or regulatory purposes. If the security meets this criterion, the decline in fair value is other-than-temporary and is recorded in earnings. The Company does not intend to sell these securities prior to maturity and it is not likely that the Company will be required to sell these securities prior to maturity; therefore, there is no indication of other-than-temporary impairment for these securities.

The contractual maturities of short-term and long-term investments and restricted deposits are as follows:



	September 30, 2014								December 31, 2013
	Investments				Restricted Deposits				Investments				Restricted Deposits
	Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value
One year or less	$	166,251	$	166,993	$	91,716	$	91,731	$	101,537	$	102,126	$	40,633	$	40,637
One year through five years	953,321		952,591		7,999		7,996		609,755		610,589		6,301		6,309
Five years through ten years	123,875		123,175		—		—		157,003		151,221		—		—
Greater than ten years	31,874		32,495		—		—		29,900		30,090		—		—
Total	$	1,275,321	$	1,275,254	$	99,715	$	99,727	$	898,195	$	894,026	$	46,934	$	46,946

Actual maturities may differ from contractual maturities due to call or prepayment options. Asset backed and mortgage backed securities are included in the one year through five years category, while cost and equity method investments and life insurance contracts are included in the five years through ten years category. The Company has an option to redeem at amortized cost substantially all of the securities included in the greater than ten years category listed above.

The Company continuously monitors investments for other-than-temporary impairment. Certain investments have experienced a decline in fair value due to changes in credit quality, market interest rates and/or general economic conditions. The Company recognizes an impairment loss for cost and equity method investments when evidence demonstrates that it is other-than-temporarily impaired. Evidence of a loss in value that is other-than-temporary may include the absence of an ability to recover the carrying amount of the investment or the inability of the investee to sustain a level of earnings that would justify the carrying amount of the investment.