Supplemental Cash Flow Information of the Operating Partnership - Reconciliation of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH:
Cash and cash equivalents	$ 605,012	$ 60,044	$ 52,415	$ 51,604
Restricted cash	16,300	16,300	6,300	119,430
Cash and cash equivalents and restricted cash	621,312	76,344	58,715	171,034
Kilroy Realty L.P. [Member]
RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH:
Cash and cash equivalents	605,012	60,044	52,415	51,604
Restricted cash	16,300	16,300	6,300	119,430
Cash and cash equivalents and restricted cash	$ 621,312	$ 76,344	$ 58,715	$ 171,034