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

Common Stock Equity Incentive Plan (Authorized Increases of Common Stock) (Details) - shares	Jan. 01, 2019	Jan. 01, 2018	Jan. 01, 2017	Jan. 01, 2016	Jan. 01, 2015	Jan. 01, 2014	Jan. 01, 2013	Jan. 01, 2012	Jan. 07, 2011	May 15, 2010
2009 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award
Authorized Shares Added	1,490,048	1,484,382	1,166,546	1,152,565	1,119,233	1,062,920	839,407	823,649	714,285	1,238,095