EARNINGS PER COMMON SHARE (DETAILS) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended			5 Months Ended	6 Months Ended
	Jan. 15, 2016	Aug. 30, 2015	Jun. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Jan. 15, 2016	Jun. 30, 2016	Jun. 30, 2015
Basic earnings per common share
Net income			$ 129,460		$ 73,371		$ 177,846	$ 239,197
Less: preferred share dividends			9,969		10,022		19,938	20,044
Net income available to common shareholders			$ 119,491		$ 63,349		$ 157,908	$ 219,153
Weighted average number of common shares outstanding - basic (in shares)			91,926,000		100,274,000		92,980,000	100,093,000
Basic earnings per common share (in usd per share)			$ 1.30		$ 0.63		$ 1.70	$ 2.19
Diluted earnings per common share
Net income available to common shareholders			$ 119,491		$ 63,349		$ 157,908	$ 219,153
Weighted average number of common shares outstanding - basic (in shares)			91,926,000		100,274,000		92,980,000	100,093,000
Share based compensation plans (in shares)			632,000		886,000		725,000	1,058,000
Weighted average number of common shares outstanding - diluted (in shares)			92,558,000		101,160,000		93,705,000	101,151,000
Diluted earnings per common share (in usd per share)			$ 1.29		$ 0.63		$ 1.69	$ 2.17
Anti-dilutive shares excluded from the dilutive computation			7,000		89,000		339,000	329,000
August 17, 2015 ASR agreement [Member]
Accelerated Share Repurchases [Line Items]
Shares repurchased (in shares)	1,358,380.00	4,149,378		4,149,378		5,507,758	1,358,380