Shareholders' Equity - Schedule of Dividend Declared (Detail)	12 Months Ended
	Dec. 31, 2017 $ / shares
Record Date One [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.075
Record Date	Aug. 07, 2017
Payment Date	Sep. 29, 2017
Record Date Two [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.075
Record Date	May 10, 2017
Payment Date	Jun. 30, 2017
Record Date Three [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.075
Record Date	Mar. 06, 2017
Payment Date	Mar. 31, 2017
Record Date Four [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.066
Record Date	Dec. 16, 2016
Payment Date	Dec. 30, 2016
Record Date Five [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.066
Record Date	Sep. 16, 2016
Payment Date	Sep. 30, 2016
Record Date Six [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.066
Record Date	Jun. 18, 2016
Payment Date	Jun. 30, 2016
Record Date Seven [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.066
Record Date	Mar. 18, 2016
Payment Date	Mar. 31, 2016
Record Date Eight [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.066
Record Date	Dec. 16, 2015
Payment Date	Dec. 30, 2015
Record Date Nine [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.066
Record Date	Sep. 18, 2015
Payment Date	Sep. 30, 2015
Record Date Ten [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.066
Record Date	Jun. 12, 2015
Payment Date	Jun. 26, 2015
Record Date Eleven [Member]
Dividends Declared [Line Items]
Dividend Per Share	$ 0.066
Record Date	Mar. 19, 2015
Payment Date	Mar. 31, 2015