Investment Securities (Tables)
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12 Months Ended |
Dec. 31, 2016 |
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| Investments, Debt and Equity Securities [Abstract] |
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| 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) | 2016 | | | | | | | | U.S. Government sponsored agency securities | $ | 132 |
| | $ | 2 |
| | $ | — |
| | $ | 134 |
| State and municipal securities | 405,274 |
| | 2,043 |
| | (15,676 | ) | | 391,641 |
| Corporate debt securities | 112,016 |
| | 1,978 |
| | (4,585 | ) | | 109,409 |
| Collateralized mortgage obligations | 604,095 |
| | 1,943 |
| | (12,178 | ) | | 593,860 |
| Mortgage-backed securities | 1,353,292 |
| | 6,546 |
| | (17,437 | ) | | 1,342,401 |
| Auction rate securities | 107,215 |
| | — |
| | (9,959 | ) | | 97,256 |
| Total debt securities | 2,582,024 |
| | 12,512 |
| | (59,835 | ) | | 2,534,701 |
| Equity securities | 12,231 |
| | 12,295 |
| | — |
| | 24,526 |
| Total | $ | 2,594,255 |
| | $ | 24,807 |
| | $ | (59,835 | ) | | $ | 2,559,227 |
| | | | | | | | | 2015 | | | | | | | | 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 |
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| 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, 2016, 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 | $ | 54,727 |
| | $ | 55,027 |
| Due from one year to five years | 28,720 |
| | 29,342 |
| Due from five years to ten years | 95,658 |
| | 96,933 |
| Due after ten years | 445,532 |
| | 417,138 |
| | 624,637 |
| | 598,440 |
| Collateralized mortgage obligations (1) | 604,095 |
| | 593,860 |
| Mortgage-backed securities (1) | 1,353,292 |
| | 1,342,401 |
| Total debt securities | $ | 2,582,024 |
| | $ | 2,534,701 |
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| 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) | 2016: | | | | | | | | Equity securities | $ | 2,005 |
| | $ | (10 | ) | | $ | — |
| | $ | 1,995 |
| Debt securities | 581 |
| | (26 | ) | | — |
| | 555 |
| Total | $ | 2,586 |
| | $ | (36 | ) | | $ | — |
| | $ | 2,550 |
| 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 |
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| Summary Of Other Than Temporary Impairment Charges Recorded In Statement Of Operations |
There were no other-than-temporary impairment charges in 2016 or 2015. In 2014, there were $30,000 of other-than-temporary impairment charges, consisting of $12,000 of impairment charges on equity securities and $18,000 of charges on pooled trust preferred securities. |
| 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: | | | | | | | | | | | | | | 2016 | | 2015 | | 2014 | | (in thousands) | Balance of cumulative credit losses on debt securities, beginning of year | $ | (11,510 | ) | | $ | (16,242 | ) | | $ | (20,691 | ) | Additions for credit losses recorded which were not previously recognized as components of earnings | — |
| | — |
| | (18 | ) | Reductions for securities sold during the period | — |
| | 4,730 |
| | 4,460 |
| Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security | — |
| | 2 |
| | 7 |
| Balance of cumulative credit losses on debt securities, end of year | $ | (11,510 | ) | | $ | (11,510 | ) | | $ | (16,242 | ) |
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| 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, 2016. There were no gross unrealized losses on equity securities as of December 31, 2016.
| | | | | | | | | | | | | | | | | | | | | | | | | | 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) | State and municipal securities | $ | 247,509 |
| | $ | (15,676 | ) | | $ | — |
| | $ | — |
| | $ | 247,509 |
| | $ | (15,676 | ) | Corporate debt securities | 11,922 |
| | (110 | ) | | 34,629 |
| | (4,475 | ) | | 46,551 |
| | (4,585 | ) | Collateralized mortgage obligations | 166,905 |
| | (3,899 | ) | | 258,237 |
| | (8,279 | ) | | 425,142 |
| | (12,178 | ) | Mortgage-backed securities | 1,137,510 |
| | (17,437 | ) | | — |
| | — |
| | 1,137,510 |
| | (17,437 | ) | Auction rate securities | — |
| | — |
| | 97,256 |
| | (9,959 | ) | | 97,256 |
| | (9,959 | ) | Total debt securities | 1,563,846 |
| | (37,122 | ) | | 390,122 |
| | (22,713 | ) | | 1,953,968 |
| | (59,835 | ) |
For comparative purposes, the following table presents gross unrealized losses and the estimated fair value of investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at 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 | ) |
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| 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: | | | | | | | | | | | | | | | | | | 2016 | | 2015 | | Amortized
Cost | | Estimated
Fair Value | | Amortized
Cost | | Estimated
Fair Value | | (in thousands) | Single-issuer trust preferred securities | $ | 43,746 |
| | $ | 39,829 |
| | $ | 44,648 |
| | $ | 39,106 |
| Subordinated debt | 46,231 |
| | 46,723 |
| | 39,610 |
| | 40,779 |
| Senior debt | 18,037 |
| | 18,433 |
| | 12,043 |
| | 12,329 |
| Pooled trust preferred securities | — |
| | 422 |
| | — |
| | 706 |
| Corporate debt securities issued by financial institutions | 108,014 |
| | 105,407 |
| | 96,301 |
| | 92,920 |
| Other corporate debt securities | 4,002 |
| | 4,002 |
| | 4,035 |
| | 4,035 |
| Available for sale corporate debt securities | $ | 112,016 |
| | $ | 109,409 |
| | $ | 100,336 |
| | $ | 96,955 |
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