INVESTMENTS - Summary of Held-To-Maturity and Available-For-Sale Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	$ 822,319	$ 2,664
Held-to-Maturity Unrealized Gains	9,956	229
Held-to-Maturity Unrealized Losses	(1,735)	0
Held-to-Maturity Market Value	830,540	2,893
Available-for-sale Securities, Amortized Cost Basis	672,824	1,421,490
Available-for-Sale Unrealized Gains	17,074	22,478
Available-for-Sale Unrealized Losses	(218)	(2,122)
Available-for-Sale Market Value	689,680	1,441,846
Securities of U.S. government agencies and corporations
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	20,844	0
Held-to-Maturity Unrealized Gains	488	0
Held-to-Maturity Unrealized Losses	0	0
Held-to-Maturity Market Value	21,332	0
Available-for-sale Securities, Amortized Cost Basis	25,772	45,757
Available-for-Sale Unrealized Gains	391	433
Available-for-Sale Unrealized Losses	0	0
Available-for-Sale Market Value	26,163	46,190
Mortgage-backed securities
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	799,583	90
Held-to-Maturity Unrealized Gains	9,184	2
Held-to-Maturity Unrealized Losses	(1,735)	0
Held-to-Maturity Market Value	807,032	92
Available-for-sale Securities, Amortized Cost Basis	615,367	1,344,015
Available-for-Sale Unrealized Gains	15,331	21,394
Available-for-Sale Unrealized Losses	(67)	(2,031)
Available-for-Sale Market Value	630,631	1,363,378
Obligations of state and other political subdivisions
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	1,892	2,574
Held-to-Maturity Unrealized Gains	284	227
Held-to-Maturity Unrealized Losses	0	0
Held-to-Maturity Market Value	2,176	2,801
Available-for-sale Securities, Amortized Cost Basis	6,332	9,270
Available-for-Sale Unrealized Gains	146	121
Available-for-Sale Unrealized Losses	0	(5)
Available-for-Sale Market Value	6,478	9,386
Other securities
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	0	0
Held-to-Maturity Unrealized Gains	0	0
Held-to-Maturity Unrealized Losses	0	0
Held-to-Maturity Market Value	0	0
Available-for-sale Securities, Amortized Cost Basis	25,353	22,448
Available-for-Sale Unrealized Gains	1,206	530
Available-for-Sale Unrealized Losses	(151)	(86)
Available-for-Sale Market Value	$ 26,408	$ 22,892

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details

- Definition

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

+ References

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+ Details

- Definition

This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

+ References+ Details

- Definition

As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

+ References+ Details

- Definition

As of the balance sheet date, the excess of carrying value (amortized cost) over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss.

+ References+ Details