Shareholders' Equity And Earnings Per Share (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended		12 Months Ended
	Dec. 19, 2008	Jan. 31, 2019	Jun. 30, 2015	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Temporary Equity [Line Items]
Cash dividends declared per common share (usd per share)		$ 0.25		$ 0.25	$ 0.19
Common stock dividends per share declared annualized (usd per share)		$ 1.00
US Treasury
Temporary Equity [Line Items]
Warrants outstanding, shares	1,643,295
Warrant termination period	10 years
Warrants exercised, shares						22,952
Common stock shares issued from exercise of warrants						16,571
Series D Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)			5,000,000	5,000,000	5,000,000	5,000,000
Preferred stock, liquidation value per share (usd per share)			$ 25	$ 25	$ 25	$ 25
Preferred stock, value			$ 125,000	$ 125,000	$ 125,000	$ 125,000
Preferred stock, dividend rate, percentage			6.50%
London Interbank Offered Rate (LIBOR) | Series D Preferred Stock
Temporary Equity [Line Items]
Preferred stock, dividend rate, percentage, variable spread			4.06%