FAIR VALUE (Fair Value of Financial Instruments) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Financial Instruments, Financial Assets [Abstract]
Available-for-sale investment securities	$ 11,675,042,000	$ 11,646,240,000
Trading securities	125,116,000	0
Loans held for investment, net	74,212,032,000	49,087,340,000
Derivative assets at fair value	251,741,000	222,491,000
Financial Instruments, Financial Liabilities [Abstract]
Derivative liabilities	287,667,000	239,311,000
Restricted cash	2,059,673,000	97,397,000
Carrying Value [Member]
Financial Instruments, Financial Assets [Abstract]
Cash and amounts due from depository institutions	4,385,648,000	4,226,947,000
Available-for-sale investment securities	11,675,042,000	11,646,240,000
Trading securities	125,116,000
Debentures of FHLB	19,957,000	19,862,000
Loans held for investment, net	74,212,032,000	49,087,340,000
Loans held for sale	290,407,000	128,949,000
Restricted Cash	2,059,673,000	97,397,000
Mortgage servicing rights	124,118,000	141,787,000
Derivative assets at fair value	282,825,000	256,885,000
Financial Instruments, Financial Liabilities [Abstract]
Deposits	49,799,792,000	49,521,406,000
Borrowings and other debt obligations	38,213,650,000	12,376,624,000
Derivative liabilities	318,751,000	273,703,000
Fair Value [Member]
Financial Instruments, Financial Assets [Abstract]
Cash and amounts due from depository institutions	4,385,648,000	4,226,947,000
Available-for-sale investment securities	11,675,042,000	11,646,240,000
Trading securities	125,116,000
Debentures of FHLB	20,000,000	20,000,000
Loans held for investment, net	74,442,476,000	49,307,888,000
Loans held for sale	290,736,000	128,949,000
Restricted Cash	2,059,673,000	97,397,000
Mortgage servicing rights	124,118,000	141,787,000
Derivative assets at fair value	282,825,000	256,885,000
Financial Instruments, Financial Liabilities [Abstract]
Deposits	49,855,974,000	49,609,846,000
Borrowings and other debt obligations	38,927,956,000	13,210,300,000
Derivative liabilities	318,751,000	273,703,000
Level 1 [Member]
Financial Instruments, Financial Assets [Abstract]
Cash and amounts due from depository institutions	4,385,648,000	4,226,947,000
Available-for-sale investment securities	10,163,000	9,841,000
Trading securities	0
Debentures of FHLB	0	0
Loans held for investment, net	0	0
Loans held for sale	0	0
Restricted Cash	2,059,673,000	97,397,000
Mortgage servicing rights	0	0
Derivative assets at fair value	0	0
Financial Instruments, Financial Liabilities [Abstract]
Deposits	42,921,497,000	41,382,336,000
Borrowings and other debt obligations	0	0
Derivative liabilities	0	0
Level 2 [Member]
Financial Instruments, Financial Assets [Abstract]
Cash and amounts due from depository institutions	0	0
Available-for-sale investment securities	10,421,007,000	11,583,459,000
Trading securities	125,116,000
Debentures of FHLB	20,000,000	20,000,000
Loans held for investment, net	94,685,000	149,796,000
Loans held for sale	290,736,000	128,949,000
Restricted Cash	0	0
Mortgage servicing rights	0	0
Derivative assets at fair value	278,723,000	256,324,000
Financial Instruments, Financial Liabilities [Abstract]
Deposits	6,934,477,000	8,227,510,000
Borrowings and other debt obligations	31,465,006,000	13,210,300,000
Derivative liabilities	318,390,000	273,306,000
Level 3 [Member]
Financial Instruments, Financial Assets [Abstract]
Cash and amounts due from depository institutions	0	0
Available-for-sale investment securities	1,243,872,000	52,940,000
Trading securities	0
Debentures of FHLB	0	0
Loans held for investment, net	74,347,791,000	49,158,092,000
Loans held for sale	0	0
Restricted Cash	0	0
Mortgage servicing rights	124,118,000	141,787,000
Derivative assets at fair value	4,102,000	561,000
Financial Instruments, Financial Liabilities [Abstract]
Deposits	0	0
Borrowings and other debt obligations	7,462,950,000	0
Derivative liabilities	$ 361,000	$ 397,000