Stockholders' equity (Details) $ / shares in Units, ft² in Millions	1 Months Ended	12 Months Ended
	Oct. 29, 2019 shares	Dec. 31, 2019 USD ($) ft² $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares
Preferred stock
Preferred stock redemption charge | $		$ (2,580,000)	$ (4,240,000)	$ (11,279,000)
Conversion of 7.00% Series D preferred stock (in shares)		578,000
Dividends declared on preferred stock | $		$ 3,204,000	$ 5,060,000	$ 7,666,000
Shares of common stock authorized		200,000,000.0	200,000,000
Shares of common stock issued and outstanding		120,800,315	111,011,816
Shares of preferred stock issued and outstanding		0
Shares of preferred stock authorized		100,000,000.0
Number of "excess stock" authorized (in shares)		200,000,000.0
Number of excess stock authorized issued and outstanding (in shares)		0
75/125 Binney Street, 500 Forbes Blvd., 5200 Illumina Way
Additional Paid in Capital [Abstract]
Area of Real Estate Property | ft²		1.3
Proceeds received for real estate joint venture | $		$ 864,200,000
Series D Convertible Preferred Stock
Preferred stock
Preferred Stock, Shares Outstanding		0	2,573,432	3,000,000.0
7.00% Series D Preferred Stock repurchased (in shares)		275,000
Number of shares converted/redeemed	2,300,000		402,000	501,115
Aggregate price on repurchase of Series D preferred stock | $		$ 9,200,000	$ 14,000,000.0	$ 17,900,000
Aggregate price on repurchase of Series D preferred stock, per share | $ / shares		$ 33.60	$ 34.77	$ 35.79
Preferred stock redemption charge | $		$ (2,600,000)	$ (4,200,000)	$ (5,800,000)
Write off of Stock Issuance Costs | $		215,000	314,000	391,000
Original issuance costs write-off | $		$ 100,000
Redemption price per share | $ / shares		$ 25.00
Payment of quarterly dividends in arrears at an annual rate (in dollars per share) | $ / shares		$ 1.75
Percentage of the closing sale price per share of the entity's common stock that the then-applicable conversion price must exceed in order for the shares to be automatically converted		150.00%
Minimum number of trading days within 30 consecutive trading days during which the closing sale price per share of entity's common stock equals or exceeds the then-applicable conversion price for the shares to be automatically converted		20 days
Number of consecutive trading day period within which the closing sale price per share of entity's common stock equals or exceeds the then-applicable conversion price for at least 20 trading days for the shares to be automatically converted		30 days
Conversion rate at a option of holders (in shares)		0.2477
Conversion rate which is equivalent to an initial conversion price per share of common stock (in dollars per share) | $ / shares		$ 100.93
Conversion rate dividend adjustment per quarter (in dollars per share) | $ / shares		$ 0.78
Conversion rate (in shares)		0.2513
Closing sales price per share that the then-applicable conversion price must exceed in order for the shares to be automatically converted | $ / shares		$ 149.46
Dividends declared on preferred stock | $		$ 3,200,000	$ 5,100,000	$ 5,200,000
Preferred stock dividends declared (per share) | $ / shares		$ 1.3125	$ 1.75	$ 1.75
Shares of preferred stock issued and outstanding		0	2,573,432
Shares of preferred stock authorized		10,000,000	10,000,000
Series E Cumulative Redeemable Preferred Stock
Preferred stock
Number of shares converted/redeemed				5,200,000
Preferred stock redemption amount | $					$ 130,000,000.0
Preferred stock redemption charge | $				$ (5,500,000)
Original issuance costs write-off | $				$ 130,350,000
Preferred stock redemption date				Apr. 14, 2017
Redemption price per share | $ / shares					$ 25.00
Preferred stock dividends declared (per share) | $ / shares		$ 0	$ 0	$ 0