Investment Securities (Tables)

12 Months Ended

Dec. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost and Fair Values of Investment Securities

The following tables present the amortized cost and estimated fair values of investment securities, which were all classified as available for sale, as of December 31:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
2015
U.S. Government securities	$	—	$	—	$	—		$	—
U.S. Government sponsored agency securities	25,154		35		(53		)	25,136
State and municipal securities	256,746		6,019		—			262,765
Corporate debt securities	100,336		2,695		(6,076		)	96,955
Collateralized mortgage obligations	835,439		3,042		(16,972		)	821,509
Mortgage-backed securities	1,154,935		10,104		(6,204		)	1,158,835
Auction rate securities	106,772		—		(8,713		)	98,059
Total Debt Securities	2,479,382		21,895		(38,018		)	2,463,259
Equity securities	14,677		6,845		(8		)	21,514
Total	$	2,494,059	$	28,740	$	(38,026	)	$	2,484,773
2014
U.S. Government securities	$	200	$	—	$	—		$	200
U.S. Government sponsored agency securities	209		5		—			214
State and municipal securities	238,250		7,231		(266		)	245,215
Corporate debt securities	99,016		5,126		(6,108		)	98,034
Collateralized mortgage obligations	917,395		5,705		(20,787		)	902,313
Mortgage-backed securities	914,797		16,978		(2,944		)	928,831
Auction rate securities	108,751		—		(7,810		)	100,941
Total Debt Securities	2,278,618		35,045		(37,915		)	2,275,748
Equity securities	33,469		14,167		(13		)	47,623
Total	$	2,312,087	$	49,212	$	(37,928	)	$	2,323,371

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 December 31, 2015, 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	$	75,458	$	75,945
Due from one year to five years	85,840		87,877
Due from five years to ten years	124,190		127,103
Due after ten years	203,520		191,990
	489,008		482,915
Collateralized mortgage obligations	835,439		821,509
Mortgage-backed securities	1,154,935		1,158,835
Total	$	2,479,382	$	2,463,259

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 gross gains and losses on the sales of equity and debt securities, and losses recognized for other-than-temporary impairment of investments:

	Gross Realized Gains		Gross Realized Losses			Other- than- temporary Impairment Losses			Net Gains
	(in thousands)
2015:
Equity securities	$	6,496	$	(1	)	$	—		$	6,495
Debt securities	2,571		—			—			2,571
Total	$	9,067	$	(1	)	$	—		$	9,066
2014:
Equity securities	$	335	$	—		$	(12	)	$	323
Debt securities	2,058		(322		)	(18		)	1,718
Total	$	2,393	$	(322	)	$	(30	)	$	2,041
2013:
Equity securities	$	4,391	$	(28	)	$	(27	)	$	4,336
Debt securities	3,787		(22		)	(97		)	3,668
Total	$	8,178	$	(50	)	$	(124	)	$	8,004

Summary Of Other Than Temporary Impairment Charges Recorded In Statement Of Operations

The following table presents a summary of other-than-temporary impairment charges recorded as decreases to investment securities gains on the consolidated statements of income, by investment security type. There were no other-than-temporary impairment charges recorded as decreases to investment securities gains in 2015.

		2014		2013
	(in thousands)
Equity securities - financial institution stocks		$	12	$	27
Pooled trust preferred securities		18		97
Total other-than-temporary impairment charges		$	30	$	124

Summary of Cumulative Other-than-Temporary Impairment Charges Recognized in Earnings for Pooled Trust Preferred Securities Held

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 December 31:

	2015			2014			2013
	(in thousands)
Balance of cumulative credit losses on debt securities, beginning of year	$	(16,242	)	$	(20,691	)	$	(23,079	)
Additions for credit losses recorded which were not previously recognized as components of earnings	—			(18		)	(97		)
Reductions for securities sold during the period	4,730			4,460			2,468
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	2			7			17
Balance of cumulative credit losses on debt securities, end of year	$	(11,510	)	$	(16,242	)	$	(20,691	)

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, as of December 31, 2015:

	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	$	9,957	$	(53	)	$	—	$	—		$	9,957	$	(53	)
Corporate debt securities	12,892		(97		)	33,036		(5,979		)	45,928		(6,076		)
Collateralized mortgage obligations	166,007		(1,467		)	467,778		(15,505		)	633,785		(16,972		)
Mortgage-backed securities	611,920		(4,783		)	63,818		(1,421		)	675,738		(6,204		)
Auction rate securities	—		—			98,059		(8,713		)	98,059		(8,713		)
Total debt securities	800,776		(6,400		)	662,691		(31,618		)	1,463,467		(38,018		)
Equity securities	—		—			14		(8		)	14		(8		)
Total	$	800,776	$	(6,400	)	$	662,705	$	(31,626	)	$	1,463,481	$	(38,026	)

Summary of Amortized Cost and Fair Values of Corporate Debt Securities

The majority of the Corporation’s available for sale corporate debt securities are issued by financial institutions. The following table presents the amortized cost and estimated fair values of corporate debt securities as of December 31:

	2015				2014
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(in thousands)
Single-issuer trust preferred securities	$	44,648	$	39,106	$	47,569	$	42,016
Subordinated debt	51,653		53,108		47,530		50,023
Pooled trust preferred securities	—		706		2,010		4,088
Corporate debt securities issued by financial institutions	96,301		92,920		97,109		96,127
Other corporate debt securities	4,035		4,035		1,907		1,907
Available for sale corporate debt securities	$	100,336	$	96,955	$	99,016	$	98,034