Earnings Per Share and Weighted-Average Shares Outstanding - Calculation of Basic Earnings Per Share (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Reduction for dividends on preferred stock or units	$ 3.2	$ 1.7	$ 9.7	$ 1.9

The amount of preferred stock dividends that is an adjustment to net income apportioned to common stockholders.

No definition available.

Name:	us-gaap_PreferredStockDividendsIncomeStatementImpact
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration