Capital Stock - Narrative (Detail)	12 Months Ended
	Dec. 31, 2017 stockholder $ / shares shares	Dec. 31, 2016 $ / shares shares	Mar. 31, 2015 $ / shares
Equity [Abstract]
Preferred stock, par value (USD per share) | $ / shares	$ 0.01	$ 0.01	$ 0.01
Preferred stock, issued (shares)	0	0
Preferred stock, authorized (shares)	500,000	500,000
Number of Stockholders | stockholder	10,214
Common stock, shares, outstanding (in shares)	17,343,839