Investment Securities

12 Months Ended

Dec. 31, 2010

Investment Securities [Abstract]

Investment Securities

4. INVESTMENT SECURITIES

Investment securities classified as current and long-term were as follows at December 31, 2010 and 2009, respectively:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
December 31, 2010
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations	$	697,816	$	14,412	$	(615	)	$	711,613
Mortgage-backed securities		1,614,569		49,783		(1,173	)		1,663,179
Tax-exempt municipal securities		2,439,659		37,294		(43,619	)		2,433,334
Mortgage-backed securities:
Residential		58,017		545		(2,675	)		55,887
Commercial		306,291		14,911		(171	)		321,031
Asset-backed securities		148,068		1,727		(44	)		149,751
Corporate debt securities		2,906,228		139,793		(13,710	)		3,032,311
Redeemable preferred stock		5,333		0		0			5,333
Total debt securities	$	8,175,981	$	258,465	$	(62,007	)	$	8,372,439
December 31, 2009
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations	$	1,005,203	$	6,683	$	(2,534	)	$	1,009,352
Mortgage-backed securities		1,675,667		24,324		(11,328	)		1,688,663
Tax-exempt municipal securities		2,195,077		52,381		(23,417	)		2,224,041
Mortgage-backed securities:
Residential		106,191		220		(10,999	)		95,412
Commercial		285,014		3,252		(8,640	)		279,626
Asset-backed securities		106,471		824		(107	)		107,188
Corporate debt securities		2,043,721		57,173		(21,326	)		2,079,568
Redeemable preferred stock		8,400		4,900		0			13,300
Total debt securities	$	7,425,744	$	149,757	$	(78,351	)	$	7,497,150

We participate in a securities lending program where we loan certain investment securities for short periods of time in exchange for collateral, consisting of cash or U.S. Government securities, initially equal to at least 102% of the fair value of the investment securities on loan. Investment securities with a fair value of $54.0 million at December 31, 2010 and $126.1 million at December 31, 2009 were on loan. At December 31, 2010, all collateral from lending our investment securities was in the form of cash which has been reinvested in money market funds and short-term asset-backed securities.

Gross unrealized losses and fair values aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position were as follows at December 31, 2010 and 2009, respectively:

	Less than 12 months					12 months or more					Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
	(in thousands)
December 31, 2010
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations	$	141,766	$	(615	)	$	0	$	0		$	141,766	$	(615	)
Mortgage-backed securities		110,358		(1,054	)		5,557		(119	)		115,915		(1,173	)
Tax-exempt municipal securities		1,168,221		(33,218	)		97,809		(10,401	)		1,266,030		(43,619	)
Mortgage-backed securities:
Residential		0		0			32,671		(2,675	)		32,671		(2,675	)
Commercial		0		0			2,752		(171	)		2,752		(171	)
Asset-backed securities		17,069		(42	)		283		(2	)		17,352		(44	)
Corporate debt securities		383,677		(9,572	)		31,464		(4,138	)		415,141		(13,710	)
Total debt securities	$	1,821,091	$	(44,501	)	$	170,536	$	(17,506	)	$	1,991,627	$	(62,007	)
December 31, 2009
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations	$	301,843	$	(2,425	)	$	2,970	$	(109	)	$	304,813	$	(2,534	)
Mortgage-backed securities		823,365		(11,005	)		6,834		(323	)		830,199		(11,328	)
Tax-exempt municipal securities		598,520		(14,286	)		198,327		(9,131	)		796,847		(23,417	)
Mortgage-backed securities:
Residential		1,771		(5	)		73,178		(10,994	)		74,949		(10,999	)
Commercial		31,941		(359	)		142,944		(8,281	)		174,885		(8,640	)
Asset-backed securities		1,930		(19	)		2,179		(88	)		4,109		(107	)
Corporate debt securities		636,833		(9,354	)		99,830		(11,972	)		736,663		(21,326	)
Total debt securities	$	2,396,203	$	(37,453	)	$	526,262	$	(40,898	)	$	2,922,465	$	(78,351	)

Approximately 96% of our debt securities were investment-grade quality, with an average credit rating of AA by S&P at December 31, 2010. Most of the debt securities that were below investment-grade were rated BB, the higher end of the below investment-grade rating scale. At December 31, 2010, 14% of our tax-exempt municipal securities were pre-refunded, generally with U.S. government and agency securities, and 25% of our tax-exempt securities were insured by bond insurers and had an equivalent S&P credit rating of AA exclusive of the bond insurers' guarantee. Our investment policy limits investments in a single issuer and requires diversification among various asset types.

The recoverability of our residential and commercial mortgage-backed securities is supported by factors such as seniority, underlying collateral characteristics and credit enhancements. Our residential and commercial mortgage-backed securities at December 31, 2010 primarily were composed of senior tranches having high credit support, with 99% of the collateral consisting of prime loans. All commercial mortgage-backed securities were rated AA+ at December 31, 2010.

All issuers of securities we own that were trading at an unrealized loss at December 31, 2010 remain current on all contractual payments. After taking into account these and other factors previously described, we believe these unrealized losses primarily were caused by an increase in market interest rates and tighter liquidity conditions in the current markets than when the securities were purchased. At December 31, 2010, we did not intend to sell the securities with an unrealized loss position in accumulated other comprehensive income, and it is not likely that we will be required to sell these securities before recovery of their amortized cost basis. As a result, we believe that the securities with an unrealized loss were not other-than-temporarily impaired at December 31, 2010.

The detail of realized gains (losses) related to investment securities and included within investment income was as follows for the years ended December 31, 2010, 2009, and 2008:

	2010			2009			2008
	(in thousands)
Gross realized gains	$	34,815		$	123,361		$	56,879
Gross realized losses		(29,169	)		(103,878	)		(136,296	)
Net realized capital gains (losses)	$	5,646		$	19,483		$	(79,417	)

There were no material other-than-temporary impairments in 2010 or 2009. Gross realized losses in 2008 included other-than-temporary impairments of $103.1 million, primarily due to investments in Lehman Brothers Holdings Inc. and certain of its subsidiaries, which filed for bankruptcy protection in 2008, as well as declines in the values of securities primarily associated with the financial services industry.

The contractual maturities of debt securities available for sale at December 31, 2010, regardless of their balance sheet classification, are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

	Amortized Cost		Fair Value
	(in thousands)
Due within one year	$	299,861	$	301,630
Due after one year through five years		1,936,215		1,991,966
Due after five years through ten years		2,072,510		2,134,576
Due after ten years		1,740,450		1,754,419
Mortgage and asset-backed securities		2,126,945		2,189,848
Total debt securities	$	8,175,981	$	8,372,439