EARNINGS PER COMMON SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings per common share
Net income	$ 177,043	$ 103,514	$ 285,828	$ 176,719
Less: Preferred share dividends	10,656	10,656	21,313	21,313
Net income available to common shareholders	$ 166,387	$ 92,858	$ 264,515	$ 155,406
Weighted average common shares outstanding - basic (in shares)	83,941	83,539	83,834	83,431
Earnings per common share (in usd per share)	$ 1.98	$ 1.11	$ 3.16	$ 1.86
Earnings per diluted common share
Net income available to common shareholders	$ 166,387	$ 92,858	$ 264,515	$ 155,406
Weighted average common shares outstanding - basic (in shares)	83,941	83,539	83,834	83,431
Share-based compensation plans (in shares)	460	445	504	422
Weighted average common shares outstanding - diluted (in shares)	84,401	83,984	84,338	83,853
Earnings per diluted common share (in usd per share)	$ 1.97	$ 1.11	$ 3.14	$ 1.85
Weighted average anti-dilutive shares excluded from the dilutive computation (in shares)	3	158	302	484