Investment Securities (Tables)

9 Months Ended

Sep. 30, 2013

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost and Fair Values of Investment Securities

The following table presents the amortized cost and estimated fair values of investment securities:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Held to Maturity at September 30, 2013	(in thousands)
Mortgage-backed securities	$	206	$	18	$	—		$	224
Available for Sale at September 30, 2013
Equity securities	$	123,111	$	8,596	$	(130	)	$	131,577
U.S. Government securities	2,250		—		—			2,250
U.S. Government sponsored agency securities	828		8		(1		)	835
State and municipal securities	288,659		7,552		(2,698		)	293,513
Corporate debt securities	108,272		5,115		(6,836		)	106,551
Collateralized mortgage obligations	1,113,753		9,373		(40,149		)	1,082,977
Mortgage-backed securities	909,292		15,209		(10,271		)	914,230
Auction rate securities	172,052		36		(17,578		)	154,510
	$	2,718,217	$	45,889	$	(77,663	)	$	2,686,443

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Held to Maturity at December 31, 2012	(in thousands)
Mortgage-backed securities	$	292	$	27	$	—		$	319
Available for Sale at December 31, 2012
Equity securities	$	118,465	$	5,016	$	(918	)	$	122,563
U.S. Government securities	325		—		—			325
U.S. Government sponsored agency securities	2,376		21		—			2,397
State and municipal securities	301,842		13,763		(86		)	315,519
Corporate debt securities	112,162		7,858		(7,178		)	112,842
Collateralized mortgage obligations	1,195,234		16,008		(123		)	1,211,119
Mortgage-backed securities	847,790		31,831		—			879,621
Auction rate securities	174,026		—		(24,687		)	149,339
	$	2,752,220	$	74,497	$	(32,992	)	$	2,793,725

Schedule of Amortized Cost and Fair Values of Debt Securities by Contractual Maturities

The amortized cost and estimated fair values of debt securities as of September 30, 2013, by contractual maturity, are shown in the following table. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

	Held to Maturity				Available for Sale
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(in thousands)
Due in one year or less	$	—	$	—	$	45,346	$	45,470
Due from one year to five years	—		—		63,113		66,924
Due from five years to ten years	—		—		197,964		201,552
Due after ten years	—		—		265,638		243,713
	—		—		572,061		557,659
Collateralized mortgage obligations	—		—		1,113,753		1,082,977
Mortgage-backed securities	206		224		909,292		914,230
	$	206	$	224	$	2,595,106	$	2,554,866

Summary of Gains and Losses from Equity and Debt Securities, and Losses Recognized from Other-than-Temporary Impairment

The following table presents information related to the gains and losses on the sales of equity and debt securities, and losses recognized for the other-than-temporary impairment of investments:

	Gross Realized Gains		Gross Realized Losses			Other-than- temporary Impairment Losses			Net Gains
Three months ended September 30, 2013			(in thousands)
Equity securities	$	2,135	$	—		$	—		$	2,135
Debt securities	617		(22		)	(97		)	498
Total	$	2,752	$	(22	)	$	(97	)	$	2,633
Three months ended September 30, 2012
Equity securities	$	—	$	—		$	(24	)	$	(24	)
Debt securities	85		—			(19		)	66
Total	$	85	$	—		$	(43	)	$	42
Nine months ended September 30, 2013
Equity securities	$	4,357	$	(28	)	$	(27	)	$	4,302
Debt securities	3,788		(22		)	(97		)	3,669
Total	$	8,145	$	(50	)	$	(124	)	$	7,971
Nine months ended September 30, 2012
Equity securities	$	2,603	$	—		$	(81	)	$	2,522
Debt securities	328		—			(19		)	309
Total	$	2,931	$	—		$	(100	)	$	2,831

Summary Of Other Than Temporary Impairment Charges Recorded In Statement Of Operations [Table Text Block]

The following table presents a summary of the cumulative credit related other-than-temporary impairment charges, recognized as components of earnings, for debt securities held by the Corporation at September 30, 2013 and 2012:

	Three Months ended September 30						Nine Months ended September 30
	2013			2012			2013			2012
	(in thousands)
Balance of cumulative credit losses on debt securities, beginning of period	$	(20,607	)	$	(22,692	)	$	(23,079	)	$	(22,781	)
Reductions for securities sold during the period	—			—			2,468			—
Additions for credit losses recorded which were not previously recognized as components of earnings	(97		)	(19		)	(97		)	(19		)
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	—			66			4			155
Balance of cumulative credit losses on debt securities, end of period	$	(20,704	)	$	(22,645	)	$	(20,704	)	$	(22,645	)

Gross Unrealized Losses and Fair Values of Investments by Category and Length of Time in Continuous Unrealized Loss Position

The following table presents the gross unrealized losses and estimated fair values of investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at September 30, 2013:

	Less than 12 months					12 months or longer					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(in thousands)
U.S. Government sponsored agency securities	$	—	$	—		$	59	$	(1	)	$	59	$	(1	)
State and municipal securities	54,679		(2,698		)	—		—			54,679		(2,698		)
Corporate debt securities	6,889		(108		)	42,989		(6,728		)	49,878		(6,836		)
Collateralized mortgage obligations	746,630		(40,149		)	—		—			746,630		(40,149		)
Mortgage-backed securities	499,406		(10,271		)	—		—			499,406		(10,271		)
Auction rate securities	87		(3		)	153,245		(17,575		)	153,332		(17,578		)
Total debt securities	1,307,691		(53,229		)	196,293		(24,304		)	1,503,984		(77,533		)
Equity securities	17		(1		)	850		(129		)	867		(130		)
	$	1,307,708	$	(53,230	)	$	197,143	$	(24,433	)	$	1,504,851	$	(77,663	)

Summary of Amortized Cost and Fair Values of Corporate Debt Securities

The following table presents the amortized cost and estimated fair value of corporate debt securities:

	September 30, 2013				December 31, 2012
	Amortized cost		Estimated fair value		Amortized cost		Estimated fair value
	(in thousands)
Single-issuer trust preferred securities	$	54,722	$	48,368	$	56,834	$	51,656
Subordinated debt	47,375		50,493		47,286		51,747
Pooled trust preferred securities	3,676		5,191		5,530		6,927
Corporate debt securities issued by financial institutions	105,773		104,052		109,650		110,330
Other corporate debt securities	2,499		2,499		2,512		2,512
Available for sale corporate debt securities	$	108,272	$	106,551	$	112,162	$	112,842