Note Net income per common share (Computation of net income (loss) per common share ("EPS"), basic and diluted) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share, Basic and Diluted [Abstract]
Net income (loss)	$ 167,925	$ 91,324
Net Income	167,925	91,324
Preferred stock dividends	(931)	(931)
Net income (loss) applicable to common stock	$ 166,994	$ 90,393
Average common shares outstanding	98,581,743	101,696,343
Average potential dilutive common shares	177,155	140,869
Average common shares outstanding - assuming dilution	98,758,898	101,837,212
Net Income per Common Share - Basic	$ 1.69	$ 0.89
Net Income per Common Share - Diluted	$ 1.69	$ 0.89