Significant Transactions During the First Quarter and Subsequent Event	3 Months Ended
Mar. 31, 2012
Significant Transactions During the First Quarter [Abstract]
Significant Transactions During the First Quarter [Text Block]	(2) Significant Transactions During the First Quarter of 2012 and Subsequent Events Acquisitions In January 2012, the Company acquired Bon Terra, a 60-unit community located adjacent to Delano in Redmond, Washington for $16.0 million. Interior finishes are of condo quality including granite countertops, stainless steel appliances and extra large windows, and the community will operate as one community with Delano. The Company also acquired Reed Square, a 100-unit community located in Sunnyvale, California for $23.0 million. In April, the Company purchased the joint venture partner's membership interest in the co-investment Essex Skyline at MacArthur Place, a 349-unit premier high-rise apartment community containing luxury amenities located in Santa Ana, California, for a total purchase price of $85 million. During the second quarter, the Company expects to record income of $2.3 million, representing an incentive partnership interest earned as a result of achieving certain performance hurdles per the joint venture agreement. The secured loan was repaid early as part of this transaction, and the property has been added to the Company's unencumbered asset pool. Notes Receivable In January 2012 the mortgage loan secured by California Hill was paid off in full for $7.3 million. The Company contributed a note receivable with a principal balance of $12.4 million, secured by land located in San Mateo, California, at an interest rate of 5% due in November 2012 and its rights to acquire the secured land to a new joint venture, referred to as Elkhorn, with Canada Pension Plan Investment Board ("CPPIB") for a 55% non-controlling interest and $5.5 million in cash. The terms of this new joint venture are substantially the same as the other CPPIB joint ventures and will be accounted for under the equity method of accounting. The joint venture has the rights to acquire the land and subsequently develop 197 units. Mortgage Notes Payable During the first quarter 2012, the Company repaid the loan secured by the Santa Clara commercial property of $10.7 million with a rate of 5%. The Company also repaid the construction loan related to the Walnut Creek land parcel held for future development of $5.6 million with a rate of LIBOR plus 350 basis points. Common Stock During the first quarter, the Company issued 221,072 shares of common stock for $31.6 million, net of commissions, at an average per share price of $144.54. From December 31, 2011 through May 3, 2012, the Company land parcel held for future development has sold 569,307 shares of common stock for $84.4 million, net of commissions, at an average price of $149.83. Private Placement Unsecured Notes During the first quarter, the Company entered into an agreement for the issuance of $200 million of private placement unsecured notes for a term of 9-years at an all-in rate of 4.3%. The notes were forward funded to close at the end of April, June and August of 2012 for $100 million at a rate of 4.27%, $50 million at a rate of 4.30% and $50 million at a rate of 4.37%, respectively. The net proceeds from the note offering are expected to be used to prepay secured mortgage debt coming due in late 2012 and 2013 at an average rate of 5.5%. As a result of the prepayment of the Skylines loan referred to above and the prepayment of secured debt coming due in 2012 and 2013, the Company may incur prepayment penalties and write-off of deferred charges up to $2.5 million during the remainder of 2012.

(2) Significant Transactions During the First Quarter of 2012 and Subsequent Events

Acquisitions

In January 2012, the Company acquired Bon Terra, a 60-unit community located adjacent to Delano in Redmond, Washington for $16.0 million. Interior finishes are of condo quality including granite countertops, stainless steel appliances and extra large windows, and the community will operate as one community with Delano. The Company also acquired Reed Square, a 100-unit community located in Sunnyvale, California for $23.0 million.

In April, the Company purchased the joint venture partner's membership interest in the co-investment Essex Skyline at MacArthur Place, a 349-unit premier high-rise apartment community containing luxury amenities located in Santa Ana, California, for a total purchase price of $85 million. During the second quarter, the Company expects to record income of $2.3 million, representing an incentive partnership interest earned as a result of achieving certain performance hurdles per the joint venture agreement. The secured loan was repaid early as part of this transaction, and the property has been added to the Company's unencumbered asset pool.

Notes Receivable

In January 2012 the mortgage loan secured by California Hill was paid off in full for $7.3 million.

The Company contributed a note receivable with a principal balance of $12.4 million, secured by land located in San Mateo, California, at an interest rate of 5% due in November 2012 and its rights to acquire the secured land to a new joint venture, referred to as Elkhorn, with Canada Pension Plan Investment Board ("CPPIB") for a 55% non-controlling interest and $5.5 million in cash. The terms of this new joint venture are substantially the same as the other CPPIB joint ventures and will be accounted for under the equity method of accounting. The joint venture has the rights to acquire the land and subsequently develop 197 units.

Mortgage Notes Payable

During the first quarter 2012, the Company repaid the loan secured by the Santa Clara commercial property of $10.7 million with a rate of 5%. The Company also repaid the construction loan related to the Walnut Creek land parcel held for future development of $5.6 million with a rate of LIBOR plus 350 basis points.

Common Stock

During the first quarter, the Company issued 221,072 shares of common stock for $31.6 million, net of commissions, at an average per share price of $144.54. From December 31, 2011 through May 3, 2012, the Company land parcel held for future development has sold 569,307 shares of common stock for $84.4 million, net of commissions, at an average price of $149.83.

Private Placement Unsecured Notes

During the first quarter, the Company entered into an agreement for the issuance of $200 million of private placement unsecured notes for a term of 9-years at an all-in rate of 4.3%. The notes were forward funded to close at the end of April, June and August of 2012 for $100 million at a rate of 4.27%, $50 million at a rate of 4.30% and $50 million at a rate of 4.37%, respectively.

The net proceeds from the note offering are expected to be used to prepay secured mortgage debt coming due in late 2012 and 2013 at an average rate of 5.5%. As a result of the prepayment of the Skylines loan referred to above and the prepayment of secured debt coming due in 2012 and 2013, the Company may incur prepayment penalties and write-off of deferred charges up to $2.5 million during the remainder of 2012.