Status of PSOs (Detail) - Performance Stock Options (PSOs) - 2013 Equity Incentive Plan	12 Months Ended
Dec. 31, 2018 $ / shares shares
Shares
Outstanding and Vested \| shares	143,335
Weighted-Average Exercise Price Per Share
Outstanding and Vested \| $ / shares	$ 23.76
Remaining Contractual Life
Outstanding and Vested	4 years

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Share based compensation arrangement by share based payment award options outstanding and vested weighted average exercise price.

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Share based compensation arrangement by share based payment award options outstanding and vested weighted average remaining contractual term.

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Share-based compensation arrangement by share-based payment award options outstanding weighted average exercise price.

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