INVESTMENTS - Summary of Held-To-Maturity and Available-For-Sale Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	$ 917,758	$ 2,664
Held-to-Maturity Unrealized Gains	1,851	229
Held-to-Maturity Unrealized Losses	(2,882)	0
Held-to-Maturity Market Value	916,727	2,893
Available-for-sale Securities, Amortized Cost Basis	719,252	1,421,490
Available-for-Sale Unrealized Gains	17,582	22,478
Available-for-Sale Unrealized Losses	(525)	(2,122)
Available-for-Sale Market Value	736,309	1,441,846
Securities of U.S. government agencies and corporations
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	31,394	0
Held-to-Maturity Unrealized Gains	30	0
Held-to-Maturity Unrealized Losses	(240)	0
Held-to-Maturity Market Value	31,184	0
Available-for-sale Securities, Amortized Cost Basis	14,983	45,757
Available-for-Sale Unrealized Gains	106	433
Available-for-Sale Unrealized Losses	(38)	0
Available-for-Sale Market Value	15,051	46,190
Mortgage-backed securities
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	884,092	90
Held-to-Maturity Unrealized Gains	1,604	2
Held-to-Maturity Unrealized Losses	(2,642)	0
Held-to-Maturity Market Value	883,054	92
Available-for-sale Securities, Amortized Cost Basis	644,795	1,344,015
Available-for-Sale Unrealized Gains	16,306	21,394
Available-for-Sale Unrealized Losses	(288)	(2,031)
Available-for-Sale Market Value	660,813	1,363,378
Obligations of state and other political subdivisions
Investment Holdings [Line Items]
Held-to-Maturity Amortized Cost	2,272	2,574
Held-to-Maturity Unrealized Gains	217	227
Held-to-Maturity Unrealized Losses	0	0
Held-to-Maturity Market Value	2,489	2,801
Available-for-sale Securities, Amortized Cost Basis	8,588	9,270
Available-for-Sale Unrealized Gains	103	121
Available-for-Sale Unrealized Losses	(1)	(5)
Available-for-Sale Market Value	8,690	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	50,886	22,448
Available-for-Sale Unrealized Gains	1,067	530
Available-for-Sale Unrealized Losses	(198)	(86)
Available-for-Sale Market Value	$ 51,755	$ 22,892

For an unclassified balance sheet, this item represents investments in debt and equity securities which are 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