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Segment Information (Details) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2016 USD ($) | Sep. 30, 2016 USD ($) | Jun. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Sep. 30, 2015 USD ($) | Jun. 30, 2015 USD ($) | Mar. 31, 2015 USD ($) | Dec. 31, 2016 USD ($) segment | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) | Aug. 31, 2015 USD ($)
Segment Reporting [Abstract] |  |  |  |  |  |  |  |  |  |  |  |
Number of reportable operating segments defined by geographical regions | segment |  |  |  |  |  |  |  |  | 3 |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Total property revenues | $ 326,905 | $ 327,078 | $ 319,562 | $ 312,178 | $ 308,646 | $ 302,522 | $ 294,101 | $ 280,229 | $ 1,285,723 | $ 1,185,498 | $ 961,591 |
Net operating income |  |  |  |  |  |  |  |  | 896,796 | 821,990 | 649,045 |
Management and other fees from affiliates |  |  |  |  |  |  |  |  | 8,278 | 8,909 | 9,347 |
Depreciation and amortization |  |  |  |  |  |  |  |  | (441,682) | (453,423) | (360,592) |
General and administrative |  |  |  |  |  |  |  |  | (40,751) | (40,090) | (40,878) |
Merger and integration expenses |  |  |  |  |  |  |  |  | 0 | (3,798) | (53,530) |
Acquisition and investment related costs |  |  |  |  |  |  |  |  | (1,841) | (2,414) | (1,878) |
Interest expense |  |  |  |  |  |  |  |  | (219,654) | (204,827) | (164,551) |
Total return swap income |  |  |  |  |  |  |  |  | 11,716 | 5,655 | 0 |
Interest and other income |  |  |  |  |  |  |  |  | 27,305 | 19,143 | 11,811 |
Equity income in co-investments |  |  |  |  |  |  |  |  | 48,698 | 21,861 | 39,893 |
Loss on early retirement of debt |  |  |  |  |  |  |  |  | (606) | (6,114) | (268) |
Gain on sale of real estate and land |  |  |  |  |  |  |  |  | 154,561 | 47,333 | 46,039 |
Deferred tax expense on gain on sale of real estate and land |  |  |  |  |  |  |  |  | (4,410) | 0 | 0 |
Gain on remeasurement of co-investment |  |  |  |  |  |  |  |  | 0 | 34,014 | 0 |
Net income |  |  |  |  |  |  |  |  | 438,410 | 248,239 | 134,438 |
Net reportable operating segments - real estate assets | 10,364,760 |  |  |  | 10,381,577 |  |  |  | 10,364,760 | 10,381,577 |  |
Real estate under development | 190,505 |  |  |  | 242,326 |  |  |  | 190,505 | 242,326 |  |
Co-investments | 1,161,275 |  |  |  | 1,036,047 |  |  | $ 13,700 | 1,161,275 | 1,036,047 |  | $ 20,400
Real estate held for sale, net | 101,957 |  |  |  | 26,879 |  |  |  | 101,957 | 26,879 |  |
Cash and cash equivalents, including restricted cash | 170,302 |  |  |  | 123,055 |  |  |  | 170,302 | 123,055 |  |
Marketable securities | 139,189 |  |  |  | 137,485 |  |  |  | 139,189 | 137,485 |  |
Notes and other receivables | 40,970 |  |  |  | 19,285 |  |  |  | 40,970 | 19,285 |  |
Prepaid expenses and other assets | 48,450 |  |  |  | 41,730 |  |  |  | 48,450 | 41,730 |  |
Total assets | 12,217,408 |  |  |  | 12,008,384 |  |  |  | 12,217,408 | 12,008,384 |  |
Reportable Geographical Components [Member] | Southern California [Member] |  |  |  |  |  |  |  |  |  |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Total property revenues |  |  |  |  |  |  |  |  | 561,094 | 507,536 | 418,495 |
Net operating income |  |  |  |  |  |  |  |  | 382,312 | 340,797 | 274,806 |
Net reportable operating segments - real estate assets | 4,924,792 |  |  |  | 4,752,174 |  |  |  | 4,924,792 | 4,752,174 |  |
Reportable Geographical Components [Member] | Northern California [Member] |  |  |  |  |  |  |  |  |  |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Total property revenues |  |  |  |  |  |  |  |  | 453,140 | 407,590 | 319,082 |
Net operating income |  |  |  |  |  |  |  |  | 325,394 | 291,168 | 223,559 |
Net reportable operating segments - real estate assets | 3,791,549 |  |  |  | 3,733,218 |  |  |  | 3,791,549 | 3,733,218 |  |
Reportable Geographical Components [Member] | Seattle Metro [Member] |  |  |  |  |  |  |  |  |  |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Total property revenues |  |  |  |  |  |  |  |  | 217,259 | 201,417 | 168,337 |
Net operating income |  |  |  |  |  |  |  |  | 148,279 | 136,579 | 112,494 |
Net reportable operating segments - real estate assets | 1,570,340 |  |  |  | 1,613,175 |  |  |  | 1,570,340 | 1,613,175 |  |
Segment Reconciling Items [Member] | Other Real Estate Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Total property revenues |  |  |  |  |  |  |  |  | 54,230 | 68,955 | 55,677 |
Net operating income |  |  |  |  |  |  |  |  | 40,811 | 53,446 | $ 38,186 |
Net reportable operating segments - real estate assets | $ 78,079 |  |  |  | $ 283,010 |  |  |  | $ 78,079 | $ 283,010 |  |

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- Definition The difference between the carrying value and the sale price of real estate or properties and land that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method. + References No definition available. + Details
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- Definition Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(12)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(11)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash -URI http://asc.fasb.org/extlink&oid=6506951 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629 + Details
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