PARENT COMPANY STATEMENTS (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended
	Jan. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets [Abstract]
Cash and cash equivalents		$ 149,647	$ 228,558	$ 324,878
Other assets		152,390	117,650
Total assets		7,095,864	7,496,800	6,488,275
Liabilities and shareholders' equity [Abstract]
Accrued interest and other liabilities		79,998	135,849
Borrowings		102,097	102,073
Shareholders' equity		875,812	902,778	774,583	607,258
Total liabilities and shareholders' equity		7,095,864	7,496,800
Revenues [Abstract]
Other income		102,180	99,246	89,222
Expenses [Abstract]
Interest on borrowings		2,520	2,716	5,801
Other expenses		14,971	16,459	12,869
(Loss) Income before tax benefit and equity in undistributed net income of subsidiaries		111,027	108,805	103,527
Income tax benefit		(32,198)	(31,737)	(30,385)
Net income		78,829	77,068	73,142
Comprehensive (loss)/income		(2,051)	102,237	111,647
Operating activities [Abstract]
Net income		78,829	77,068	73,142
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Net change in other assets and other liabilities		11,247	292	14,268
Net cash provided by (used in) operating activities		103,184	108,424	94,378
Investing activities [Abstract]
Net cash (used in) provided by investing activities		553,258	(264,260)	(22,695)
Financing activities [Abstract]
Issuance of common stock	57,500	15,239	64,145	5,351
Net cash provided by (used in) financing activities		(735,353)	59,516	41,358
Change in cash and cash equivalents		(78,911)	(96,320)	113,041
Cash and cash equivalents at beginning of year	324,878	228,558	324,878	211,837
Cash and cash equivalents at end of year		149,647	228,558	324,878
Supplemental disclosures of cash flow information [Abstract]
Cash paid for interest		30,141	51,541	61,564
Supplemental disclosures of noncash financing activities [Abstract]
Dividends declared and unpaid		11,332	10,699	9,609
Parent Company [Member]
Assets [Abstract]
Cash and cash equivalents		83,783	43,800	38,853
Investment securities		3,601	3,587
Investment in and advances to subsidiaries		895,211	961,718
Other assets		8,847	8,613
Total assets		991,442	1,017,718
Liabilities and shareholders' equity [Abstract]
Accrued interest and other liabilities		13,533	12,867
Borrowings		102,097	102,073
Shareholders' equity		875,812	902,778
Total liabilities and shareholders' equity		991,442	1,017,718
Revenues [Abstract]
Dividends from subsidiaries		66,000	0	52,251
Interest and dividends on investments		91	98	87
Other income		9	198	0
Total revenues		66,100	296	52,338
Expenses [Abstract]
Interest on borrowings		2,520	2,716	5,815
Other expenses		61	155	273
Total expenses		2,581	2,871	6,088
(Loss) Income before tax benefit and equity in undistributed net income of subsidiaries		63,519	(2,575)	46,250
Income tax benefit		862	1,274	2,237
(Loss) Income before equity in undistributed net income of subsidiaries		64,381	(1,301)	48,487
Equity in undistributed net income of subsidiaries		14,448	78,369	24,655
Net income		78,829	77,068	73,142
Comprehensive (loss)/income		(2,051)	102,237	111,647
Operating activities [Abstract]
Net income		78,829	77,068	73,142
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
(Gain)/loss on sale of investments		(9)	0	0
Equity in undistributed net income of subsidiaries		(14,448)	(78,369)	(24,655)
Net change in other assets and other liabilities		(221)	(746)	(504)
Net cash provided by (used in) operating activities		64,151	(2,047)	47,983
Investing activities [Abstract]
Purchase of investment securities		0	(3)	0
Proceeds from sale of investment securities		114	30	2
Repayments from subsidiaries, net		0	0	51
Capital contributions to subsidiaries		0	(20,081)	(102,462)
Net cash (used in) provided by investing activities		114	(20,054)	(102,409)
Financing activities [Abstract]
Issuance of common stock		19,200	67,813	91,714
Cash dividends paid		(43,482)	(40,765)	(34,404)
Net cash provided by (used in) financing activities		(24,282)	27,048	57,310
Change in cash and cash equivalents		39,983	4,947	2,884
Cash and cash equivalents at beginning of year	38,853	43,800	38,853	35,969
Cash and cash equivalents at end of year		83,783	43,800	38,853
Supplemental disclosures of cash flow information [Abstract]
Cash paid for interest		2,521	2,738	5,959
Supplemental disclosures of noncash financing activities [Abstract]
Dividends declared and unpaid		$ 11,332	$ 10,699	$ 9,609