The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Capital Stock - Schedule of Vesting Shares Subject to Repurchase (Detail) - Restricted shares subject to repurchase [Member] - shares	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Amortization Expense [Line Items]
Unvested shares	4,197,396	1,343,764	1,456,987
1st quarter 2016 [Member]
Amortization Expense [Line Items]
Unvested shares	370,570
1st quarter 2017 [Member]
Amortization Expense [Line Items]
Unvested shares	207,170
1st quarter 2018 [Member]
Amortization Expense [Line Items]
Unvested shares	3,619,656