Basis of Presentation (Detail) - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended
	Aug. 03, 2017	Sep. 30, 2017	Sep. 30, 2016	Apr. 27, 2017
Accounting Policies [Abstract]
Common stock, shares authorized (in shares)		450,000,000		450,000,000
Preferred stock, shares authorized (in shares)		50,000,000		50,000,000
Class of Stock [Line Items]
Proceeds from issuance of preferred stock, net		$ 98,101	$ 0
Series B Preferred Stock
Class of Stock [Line Items]
Shares issued (in shares)	4,000,000.0
Liquidation preference per share (usd per share)	$ 25
Shares issued	$ 100,000
Preferred stock dividend rate	5.50%
Proceeds from issuance of preferred stock, net	$ 98,100
London Interbank Offered Rate (LIBOR) [Member] | Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock dividend rate, basis spread	3.578%