Real Estate Properties - Summary of Properties Held for Sale (Details) - Subsequent event - Held-for-sale - 1601 Dry Creek Drive	1 Months Ended
May 31, 2018 ft² building property
Real Estate Properties [Line Items]
Number of Properties \| property	1
Number of Buildings \| building	1
Square Footage (in sqft) \| ft²	552,865

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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