Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Equity Incentive Plans - Authorized Shares of Common Stock for Issuance (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
2015 Plan and the 2015 Directors’ Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Authorized shares of common stock for issuance, Number of Shares	1,250,000
2005 Plan and the Directors’ Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Authorized shares of common stock for issuance, Number of Shares	175,000	158,751	2,319,812