Quarterly report pursuant to Section 13 or 15(d)

Summary of Changes in Stockholders Equity (Parenthetical) (Detail)

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Summary of Changes in Stockholders Equity (Parenthetical) (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Equity [Abstract]    
Cumulative effect of change in accounting principle, taxes $ 13,079  
Amount per Share of Common Stock $ 0.32 $ 0.29
Record Date Mar. 08, 2018 Mar. 08, 2017
Payable Date Mar. 22, 2018 Mar. 20, 2017