Summary of Significant Accounting Policies - Components of rental income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Property operating income	$ 285,304hr_PropertyOperatingIncome	$ 251,403hr_PropertyOperatingIncome	$ 233,662hr_PropertyOperatingIncome
Single-tenant net lease	65,252hr_SingleTenantNetLeasesRentalIncome	51,467hr_SingleTenantNetLeasesRentalIncome	42,183hr_SingleTenantNetLeasesRentalIncome
Straight-line rent	10,969us-gaap_StraightLineRent	9,452us-gaap_StraightLineRent	6,599us-gaap_StraightLineRent
Rental income	$ 361,525us-gaap_RealEstateRevenueNet	$ 312,322us-gaap_RealEstateRevenueNet	$ 282,444us-gaap_RealEstateRevenueNet

Rents earned, tenant reimbursements, and other tenant revenue from leases in multi-tenanted buildings based on the terms of the contractual arrangements.

No definition available.

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- Definition

Single-Tenant Net Lease Rental Income

+ References

No definition available.

+ Details

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- Details

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- Definition

The aggregate revenue from real estate operations during the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(e))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

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- Definition

Difference between actual rental income due and rental income recognized on a straight-line basis.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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