Minimum percent based on the employee relevant income is required to be made as the Company's contribution.

No definition available.

Name:	ntp_DefinedCompanyContributionsPercentage
Namespace Prefix:	ntp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represent the retirement age for employees.

+ References

No definition available.

+ Details

Name:	ntp_EmployeesRetirementAge
Namespace Prefix:	ntp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents maximum eligible age for employees.

+ References

No definition available.

+ Details

Name:	ntp_MaximumEmployeeEligibilityAge
Namespace Prefix:	ntp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents minimum eligible age for employees.

+ References

No definition available.

+ Details

Name:	ntp_MinimumEmployeeEligibilityAge
Namespace Prefix:	ntp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum days of services under the employment to be eligible to Mandatory Provident Fund.

+ References

No definition available.

+ Details

Name:	ntp_MinimumEmployeeServicePeriodForPlanEligibility
Namespace Prefix:	ntp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of Employer Contributions for which Staff Entitled

+ References

No definition available.

+ Details

Name:	ntp_PercentageOfEmployerContributionsForWhichStaffEntitled
Namespace Prefix:	ntp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Required percentage of stipulated salary set by the local government for the Company's contributions to the retirement benefit schemes.

+ References

No definition available.

+ Details

Name:	ntp_PercentageOfSalaryContributedTowardsEmployeeBenefitPlans
Namespace Prefix:	ntp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

+ Details

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Definition

Maximum amount the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=ntp_LocalGovernmentOfWuxiMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Staff Retirement Plans - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 Y	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Line Items]
Age of employees to be eligible to Mandatory Provident Fund, Minimum	18ntp_MinimumEmployeeEligibilityAge
Age of employees to be eligible to Mandatory Provident Fund, Maximum	64ntp_MaximumEmployeeEligibilityAge
Minimum service duration to be eligible to Mandatory Provident Fund	60 days
Contribution made to Mandatory Provident Fund, based on staff's relevant income	5.00%
Maximum contribution per employee to Mandatory Provident Fund	$ 3
Retirement age of employees	65ntp_EmployeesRetirementAge
Percentage of employer contributions for which staff are entitled	100.00%
Cost of employer contribution	$ 402	$ 2,545	$ 3,863
Local governments of Wuxi
Defined Contribution Plan Disclosure [Line Items]
Percentage of salary required for contribution	20.00%
Minimum \| Local Governments of Shenzhen
Defined Contribution Plan Disclosure [Line Items]
Percentage of salary required for contribution	13.00%
Maximum \| Local Governments of Shenzhen
Defined Contribution Plan Disclosure [Line Items]
Percentage of salary required for contribution	14.00%