Mandatorily Redeemable Preferred Stock - Additional Information (Detail) - Mandatorily Redeemable Preferred Stock [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Preferred stock, shares authorized	350,000,000.0	350,000,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares issued	21,202	21,202
Preferred stock, shares outstanding	21,202	21,202
Preferred stock, dividend rate (as a percent)	8.00%	8.00%
Preferred stock, redemption value (in dollars per share)	$ 1,000	$ 1,000
Estimated fair value	$ 21,300,000	$ 21,200,000