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Sale of Equity Securities - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
Sep. 14, 2016
Jan. 12, 2016
Equity [Abstract]    
Issuance of common stock, shares 5,062,892 3,157,894
Common stock price per share $ 39.75 $ 47.50
Proceeds from public offering of common stock, net of commissions and underwriting discounts and estimated offering expenses $ 189.2 $ 140.4