Supplemental Cash Flow Information of the Operating Partnership - Reconciliation of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH:
Cash and cash equivalents	$ 762,134	$ 60,044	$ 49,693	$ 51,604
Restricted cash	16,300	16,300	6,300	119,430
Cash and cash equivalents and restricted cash	778,434	76,344	55,993	171,034
Kilroy Realty L.P. [Member]
RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH:
Cash and cash equivalents	762,134	60,044	49,693	51,604
Restricted cash	16,300	16,300	6,300	119,430
Cash and cash equivalents and restricted cash	$ 778,434	$ 76,344	$ 55,993	$ 171,034