Capital Stock - Common Stock (Detail) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Class of Stock [Line Items]
Stock repurchase program, authorized amount	$ 150,000,000
Stock repurchased during period (in shares)	1.4
Stock repurchased during period, average price (in dollars per share)	$ 15.34
Stock repurchased during period	$ 22,066,000	$ 0
Remaining authorized repurchase amount	128,000,000
Common dividends declared	93,479,000	$ 93,613,000
Dividends declared per share of common stock (usd per share)		$ 0.50
Regular Dividend
Class of Stock [Line Items]
Common dividends declared	$ 93,000,000	$ 94,000,000