Net Income Available to Common Unitholders Per Unit of the Operating Partnership (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Numerator:
Income (loss) from continuing operations	$ 19,417	[1],[2]	$ 13,168	[1],[2]	$ 15,854	[1],[2]	$ 10,874	[1],[2]	$ 5,038	[1],[2]	$ 3,180	[1],[2]	$ 6,942	[1],[2]	$ (225)	[1],[2]	$ 59,313		$ 14,935		$ (5,475)
Income from continuing operations attributable to noncontrolling interests in consolidated subsidiaries																	(966)		(36)		656
Preferred dividends and distributions	(3,312)	[1]	(3,313)	[1]	(3,312)	[1]	(3,313)	[1]	(3,312)	[1]	(3,312)	[1]	(3,313)	[1]	(3,313)	[1]	(13,250)		(13,250)		(21,088)
Allocation to participating securities (1)																	(1,699)	[3]	(1,689)	[3]	(1,602)	[3]
Numerator for basic and diluted income (loss) from continuing operations available to common unitholders																	43,398		(40)		(27,509)
Income from discontinued operations	12,013	[1],[2]	6,135	[1],[2]	15,289	[1],[2]	91,058	[1],[2]	18,009	[1],[2]	5,847	[1],[2]	3,161	[1],[2]	2,613	[1],[2]	124,495		29,630		282,576
Loss (income) from discontinued operations attributable to noncontrolling interests in consolidated subsidiaries																	(2,623)		(649)		(6,843)
Numerator for basic and diluted net income available to common unitholders																	165,270		28,941		248,224
Denominator:
Basic weighted average vested shares outstanding																	83,090,235		77,343,853		69,639,623
Effect of dilutive securities – contingently issuable shares and stock options																	1,877,485		0		0
Diluted weighted average vested units and common unit equivalents outstanding																	84,967,720		77,343,853		69,639,623
Basic earnings per unit:
Income (loss) from continuing operations available to common stockholders per share (dollars per share)																	$ 0.52		$ 0.00		$ (0.40)
Income from discontinued operations per common unit (dollars per unit)																	$ 1.47		$ 0.37		$ 3.96
Net income available to common unitholders per unit (dollars per unit)	$ 0.32	[1]	$ 0.18	[1]	$ 0.33	[1]	$ 1.17	[1]	$ 0.23	[1]	$ 0.07	[1]	$ 0.08	[1]	$ (0.02)	[1]	$ 1.99		$ 0.37		$ 3.56
Diluted earnings per unit:
Income (loss) from continuing operations available to common unitholders per unit (dollars per unit)																	$ 0.51		$ 0.00		$ (0.40)
Income from discontinued operations per common unit (dollars per unit)																	$ 1.44		$ 0.37		$ 3.96
Net income available to common unitholders per unit (dollars per unit)	$ 0.32	[1]	$ 0.18	[1]	$ 0.32	[1]	$ 1.14	[1]	$ 0.23	[1]	$ 0.07	[1]	$ 0.08	[1]	$ (0.02)	[1]	$ 1.95		$ 0.37		$ 3.56
Kilroy Realty, L.P. [Member]
Numerator:
Income (loss) from continuing operations	19,417	[4],[5]	13,168	[4],[5]	15,854	[4],[5]	10,874	[4],[5]	5,038	[4],[5]	3,180	[4],[5]	6,942	[4],[5]	(225)	[4],[5]	59,313		14,935		(5,475)
Income from continuing operations attributable to noncontrolling interests in consolidated subsidiaries																	(247)		(225)		(176)
Preferred dividends and distributions	(3,312)	[4]	(3,313)	[4]	(3,312)	[4]	(3,313)	[4]	(3,312)	[4]	(3,312)	[4]	(3,313)	[4]	(3,313)	[4]	(13,250)		(13,250)		(21,088)
Allocation to participating securities (1)																	(1,699)	[3]	(1,689)	[3]	(1,602)	[3]
Numerator for basic and diluted income (loss) from continuing operations available to common unitholders																	44,117		(229)		(28,341)
Income from discontinued operations	12,013	[4],[5]	6,135	[4],[5]	15,289	[4],[5]	91,058	[4],[5]	18,009	[4],[5]	5,847	[4],[5]	3,161	[4],[5]	2,613	[4],[5]	124,495		29,630		282,576
Loss (income) from discontinued operations attributable to noncontrolling interests in consolidated subsidiaries																	(13)		1		(462)
Numerator for basic and diluted net income available to common unitholders																	$ 168,599		$ 29,402		$ 253,773
Denominator:
Basic weighted average vested shares outstanding																	84,894,498		79,166,260		71,403,258
Effect of dilutive securities – contingently issuable shares and stock options																	1,877,485		0		0
Diluted weighted average vested units and common unit equivalents outstanding																	86,771,983		79,166,260		71,403,258
Basic earnings per unit:
Income (loss) from continuing operations available to common stockholders per share (dollars per share)																	$ 0.52		$ 0.00		$ (0.40)
Income from discontinued operations per common unit (dollars per unit)																	$ 1.47		$ 0.37		$ 3.96
Net income available to common unitholders per unit (dollars per unit)	$ 0.32	[4]	$ 0.18	[4]	$ 0.33	[4]	$ 1.17	[4]	$ 0.23	[4]	$ 0.07	[4]	$ 0.08	[4]	$ (0.02)	[4]	$ 1.99		$ 0.37		$ 3.56
Diluted earnings per unit:
Income (loss) from continuing operations available to common unitholders per unit (dollars per unit)																	$ 0.51		$ 0.00		$ (0.40)
Income from discontinued operations per common unit (dollars per unit)																	$ 1.43		$ 0.37		$ 3.96
Net income available to common unitholders per unit (dollars per unit)	$ 0.31	[4]	$ 0.18	[4]	$ 0.32	[4]	$ 1.14	[4]	$ 0.23	[4]	$ 0.07	[4]	$ 0.08	[4]	$ (0.02)	[4]	$ 1.94		$ 0.37		$ 3.56

[1] The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. The summation of the quarterly net income (loss) available to common stockholders per share does not equal the annual number reported on the consolidated statements of operations due to the Company's public offerings of common stock and its at-the-market stock offering programs that occurred during the years ended December 31, 2014 and 2013.

[2] All periods have been adjusted from amounts previously disclosed in our quarterly filings on Form 10-Q to reclassify amounts related to discontinued operations (see Note 18 “Discontinued Operations” for additional information).

[3] Participating securities include nonvested shares, certain time-based RSUs and vested market measure-based RSUs.

[4] The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. The summation of the quarterly net income (loss) available to common unitholders per unit does not equal the annual number reported on the consolidated statements of operations due to the impact of the Company's public offerings of common stock and its at-the-market stock offering programs that occurred during the years ended December 31, 2014 and 2013.

[5] All periods have been adjusted from amounts previously disclosed in our quarterly filings on Form 10-Q to reclassify amounts related to discontinued operations (see Note 18 “Discontinued Operations”).