Real Estate and Accumulated Depreciation Activity of Real Estate and Accumulated Depreciation (BPLP) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Real Estate, Balance at the beginning of the year	$ 21,058,714	$ 20,114,576	$ 19,451,683
Real Estate, Additions to / improvements of real estate	1,043,379	1,099,286	977,287
Real Estate, Assets sold / written off	(496,548)	(155,148)	(314,394)
Real Estate, Balance at the end of the year	21,605,545	21,058,714	20,114,576
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Accumulated depreciation, Balance at beginning of the year	4,566,570	4,201,891	3,905,940
Accumulated depreciation, Depreciation expense	533,342	497,059	560,024
Accumulated depreciation, Assets sold / written off	(228,810)	(132,380)	(264,073)
Accumulated depreciation, Balance at end of the year	4,871,102	4,566,570	4,201,891
Boston Properties Limited Partnership
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Real Estate, Balance at the beginning of the year	20,647,236	19,701,185	19,031,289
Real Estate, Additions to / improvements of real estate	1,043,379	1,099,286	977,287
Real Estate, Assets sold / written off	(483,426)	(153,235)	(307,391)
Real Estate, Balance at the end of the year	21,207,189	20,647,236	19,701,185
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Accumulated depreciation, Balance at beginning of the year	4,473,895	4,116,020	3,826,862
Accumulated depreciation, Depreciation expense	525,584	488,919	548,397
Accumulated depreciation, Assets sold / written off	(225,679)	(131,044)	(259,239)
Accumulated depreciation, Balance at end of the year	$ 4,773,800	$ 4,473,895	$ 4,116,020