Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v2.4.1.9
Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
 3 Months Ended
Mar. 31, 2015
Summary Of Significant Accounting Policies [Line Items]  
Maturity period of highly liquid investments Three months or less
Level 1 [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Liabilities 0us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Level 2 [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Liabilities 0us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member