NET INCOME PER COMMON SHARE - Components of Computation of Basic and Diluted Net Income Per Common Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Numerator for basic net income per common share [Abstract]
Net income	$ 36,973		$ 24,702		$ 29,894		$ 34,918		$ 35,084	$ 40,037	$ 43,335	$ 45,170	$ 126,487		$ 163,626		$ 160,204
Preferred share dividends													(17,536)		(21,021)		(20,369)
Redemption preference premiums paid on Series A and Series B preferred shares													(19,924)	[1]	0	[1]	0	[1]
Unvested stock award participation in earnings													(139)		(372)		(579)
Numerator for basic net income per common share													88,888		142,233		139,256
Denominator for basic net income per common share [Abstract]
Weighted average common shares outstanding (in shares)													95,679		95,115		79,784
Average unvested stock awards outstanding (in shares)													(506)		(522)		(468)
Denominator for basic net income per common share (in shares)													95,173		94,593		79,316
Basic net income per common share (in dollars per share)	$ 0.35	[2]	$ 0.23	[2]	$ 0.04	[2]	$ 0.31	[2]	$ 0.31	$ 0.35	$ 0.40	$ 0.45	$ 0.93		$ 1.50		$ 1.76
Numerator for diluted net income per common share [Abstract]
Net income available to common stockholders													88,888		142,233		139,256
Dividends on dilutive convertible preferred shares													44		298		298
Numerator for diluted net income per common share													$ 88,932		$ 142,531		$ 139,554
Denominator for diluted net income per common share [Abstract]
Basic weighted average common shares outstanding (in shares)													95,173		94,593		79,316
Net effect of dilutive stock and option awards (in shares)													145		111		71
Net effect of dilutive convertible preferred shares (in shares)													75		308		309
Denominator for diluted net income per common share (in shares)													95,393		95,012		79,696
Diluted net income per common share (in dollars per share)	$ 0.35	[2]	$ 0.23	[2]	$ 0.04	[2]	$ 0.31	[2]	$ 0.31	$ 0.35	$ 0.40	$ 0.44	$ 0.93		$ 1.50		$ 1.75

[1] The Series A and Series B preferred shares were redeemed on June 13, 2013 (See NOTE 11).

[2] Includes $0.23 associated with redemption preference premiums paid and other one-time effects of the second quarter’s preferred capital transactions.