Investment Securities (Tables)

3 Months Ended

Mar. 31, 2014

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, which were all classified as available for sale:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
March 31, 2014
Equity securities	$	34,231	$	11,524	$	(21	)	$	45,734
U.S. Government securities	526		—		—			526
U.S. Government sponsored agency securities	275		6		(1		)	280
State and municipal securities	278,019		7,190		(1,756		)	283,453
Corporate debt securities	100,348		6,292		(6,088		)	100,552
Collateralized mortgage obligations	1,031,968		7,638		(32,869		)	1,006,737
Mortgage-backed securities	914,502		13,582		(11,881		)	916,203
Auction rate securities	159,379		2		(11,668		)	147,713
	$	2,519,248	$	46,234	$	(64,284	)	$	2,501,198

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
December 31, 2013
Equity securities	$	33,922	$	12,355	$	(76	)	$	46,201
U.S. Government securities	525		—		—			525
U.S. Government sponsored agency securities	720		7		(1		)	726
State and municipal securities	281,810		6,483		(3,444		)	284,849
Corporate debt securities	100,468		5,685		(7,404		)	98,749
Collateralized mortgage obligations	1,069,138		8,036		(44,776		)	1,032,398
Mortgage-backed securities	949,328		13,881		(17,497		)	945,712
Auction rate securities	172,299		234		(13,259		)	159,274
	$	2,608,210	$	46,681	$	(86,457	)	$	2,568,434

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 March 31, 2014, 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.

		Amortized Cost		Estimated Fair Value
	(in thousands)
Due in one year or less		$	30,424	$	30,517
Due from one year to five years		67,544		71,350
Due from five years to ten years		199,377		203,240
Due after ten years		241,202		227,417
		538,547		532,524
Mortgage-backed securities		914,502		916,203
Collateralized mortgage obligations		1,031,968		1,006,737
		$	2,485,017	$	2,455,464

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 gross realized gains and losses on the sales of equity and debt securities:

	Gross Realized Gains		Gross Realized Losses			Net Gains
Three months ended March 31, 2014	(in thousands)
Equity securities	$	1	$	—		$	1
Debt securities	322		(323		)	(1		)
Total	$	323	$	(323	)	$	—
Three months ended March 31, 2013
Equity securities	$	1,139	$	—		$	1,139
Debt securities	1,334		—			1,334
Total	$	2,473	$	—		$	2,473

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 March 31, 2014 and 2013:

	Three months ended March 31
	2014			2013
	(in thousands)
Balance of cumulative credit losses on debt securities, beginning of period	$	(20,691	)	$	(23,079	)
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	4			—
Balance of cumulative credit losses on debt securities, end of period	$	(20,687	)	$	(23,079	)

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 March 31, 2014:

	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	$	—	$	—		$	50	$	(1	)	$	50	$	(1	)
State and municipal securities	50,286		(1,510		)	3,996		(246		)	54,282		(1,756		)
Corporate debt securities	3,939		(58		)	38,804		(6,030		)	42,743		(6,088		)
Collateralized mortgage obligations	416,584		(13,921		)	313,758		(18,948		)	730,342		(32,869		)
Mortgage-backed securities	621,165		(11,881		)	—		—			621,165		(11,881		)
Auction rate securities	—		—			147,619		(11,668		)	147,619		(11,668		)
Total debt securities	1,091,974		(27,370		)	504,227		(36,893		)	1,596,201		(64,263		)
Equity securities	3		(1		)	118		(20		)	121		(21		)
	$	1,091,977	$	(27,371	)	$	504,345	$	(36,913	)	$	1,596,322	$	(64,284	)

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:

	March 31, 2014				December 31, 2013
	Amortized cost		Estimated fair value		Amortized cost		Estimated fair value
	(in thousands)
Single-issuer trust preferred securities	$	47,502	$	41,879	$	47,481	$	40,531
Subordinated debt	47,436		50,429		47,405		50,327
Pooled trust preferred securities	2,825		5,659		2,997		5,306
Corporate debt securities issued by financial institutions	97,763		97,967		97,883		96,164
Other corporate debt securities	2,585		2,585		2,585		2,585
Available for sale corporate debt securities	$	100,348	$	100,552	$	100,468	$	98,749