Capital Stock	6 Months Ended
Jun. 30, 2015
Equity [Abstract]
Capital Stock	Capital Stock In May 2015, the Company issued 37,375,000 shares of its Class A common stock in an underwritten public offering at a price of $22.50 per share, which included the underwriters’ exercise of their over-allotment option in full. The offering generated net proceeds of $806,500,000 after deducting underwriting discounts, commissions and other offering expenses. The Company used $386,156,000 of the net proceeds to finance the June 2015 acquisition of our partner’s 49% equity interest in seven life science office properties and two parking facilities at University Park at MIT, a mixed-use life science office campus in Cambridge, Massachusetts. Subsequent to the acquisition, the Company owns 100% of these assets. The Company also used $295,979,000 of the remaining net proceeds to retire a combination of nonrecourse mortgage debt and revolving credit facility borrowings subsequent to the public offering. The remaining proceeds of $124,365,000 are expected to be used to further reduce debt and for general operating purposes. During the three months ended March 31, 2015, the Company issued shares of Class A common stock in connection with the privately negotiated exchange transactions involving a portion of the Company’s 2016, 2018 and 2020 Senior Notes. See Note D – Convertible Senior Debt for detailed information on these Class A common stock issuances, as well as the receipt of shares of Class A common stock in connection with the termination of a convertible note hedge related to the 2016 Senior Notes. Subsequent to June 30, 2015, the Company issued shares of Class A common stock in connection with additional privately negotiated exchange transactions involving a portion of the Company’s 2016, 2018 and 2020 Senior Notes. See Note D – Convertible Senior Debt for detailed information on these Class A common stock issuances.

Capital Stock

6 Months Ended

Jun. 30, 2015

In May 2015, the Company issued 37,375,000 shares of its Class A common stock in an underwritten public offering at a price of $22.50 per share, which included the underwriters’ exercise of their over-allotment option in full. The offering generated net proceeds of $806,500,000 after deducting underwriting discounts, commissions and other offering expenses. The Company used $386,156,000 of the net proceeds to finance the June 2015 acquisition of our partner’s 49% equity interest in seven life science office properties and two parking facilities at University Park at MIT, a mixed-use life science office campus in Cambridge, Massachusetts. Subsequent to the acquisition, the Company owns 100% of these assets. The Company also used $295,979,000 of the remaining net proceeds to retire a combination of nonrecourse mortgage debt and revolving credit facility borrowings subsequent to the public offering. The remaining proceeds of $124,365,000 are expected to be used to further reduce debt and for general operating purposes.

During the three months ended March 31, 2015, the Company issued shares of Class A common stock in connection with the privately negotiated exchange transactions involving a portion of the Company’s 2016, 2018 and 2020 Senior Notes. See Note D – Convertible Senior Debt for detailed information on these Class A common stock issuances, as well as the receipt of shares of Class A common stock in connection with the termination of a convertible note hedge related to the 2016 Senior Notes.

Subsequent to June 30, 2015, the Company issued shares of Class A common stock in connection with additional privately negotiated exchange transactions involving a portion of the Company’s 2016, 2018 and 2020 Senior Notes. See Note D – Convertible Senior Debt for detailed information on these Class A common stock issuances.