Distributions - Summary of Distributions Paid Including Activity in Plan as well as Limited Partnership Units Issued from Reinvestment of Unit Distributions (Detail) - USD ($) $ / shares in Units, $ in Thousands												1 Months Ended	12 Months Ended
	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividends [Line Items]
Preferred Stockholders													$ 12,390	$ 12,402	$ 12,375
Common Stockholders													48,568	46,306	44,576
Limited Partnership Unitholders													$ 16,642	$ 15,981	$ 15,268
Common Stock Shares Issued (in shares)													430,462,000	572,928	266,011
Limited Partnership Units Issued (in shares)													60,936,000	107,433	111,351
October 31
Dividends [Line Items]
Preferred Stockholders	$ 3,531				$ 2,953				$ 3,094
Common Stockholders	12,251				11,706				11,221
Limited Partnership Unitholders	$ 4,173				$ 4,062				$ 3,838
Common Stock Shares Issued (in shares)	104,558,000				216,476				82,991
Discounted Share Price (in usd per share)	$ 52.84				$ 49.34				$ 59.33
Limited Partnership Units Issued (in shares)	13,747,000				13,867				15,596
Average Unit Price (in usd per share)	$ 53.73				$ 50.20				$ 60.08
July 31
Dividends [Line Items]
Preferred Stockholders		$ 2,953				$ 2,953				$ 3,094
Common Stockholders		12,195				11,590				11,160
Limited Partnership Unitholders		$ 4,166				$ 4,055				$ 3,830
Common Stock Shares Issued (in shares)		105,753,000				201,500				85,731
Discounted Share Price (in usd per share)		$ 53.66				$ 51.68				$ 57.40
Limited Partnership Units Issued (in shares)		13,406,000				13,107				16,021
Average Unit Price (in usd per share)		$ 54.56				$ 52.60				$ 58.13
April 30
Dividends [Line Items]
Preferred Stockholders			$ 2,953				$ 2,672				$ 3,094
Common Stockholders			12,116				11,545				11,119
Limited Partnership Unitholders			$ 4,155				$ 3,942				$ 3,810
Common Stock Shares Issued (in shares)			99,804,000				85,202				51,003
Discounted Share Price (in usd per share)			$ 51.38				$ 47.54				$ 59.64
Limited Partnership Units Issued (in shares)			20,041,000				42,422				40,623
Average Unit Price (in usd per share)			$ 51.99				$ 47.83				$ 59.96
January 31
Dividends [Line Items]
Preferred Stockholders				$ 2,953				$ 3,824				$ 3,093
Common Stockholders				12,006				11,465				11,076
Limited Partnership Unitholders				$ 4,148				$ 3,922				$ 3,790
Common Stock Shares Issued (in shares)				120,347,000				69,750				46,286
Discounted Share Price (in usd per share)				$ 51.28				$ 52.71				$ 61.85
Limited Partnership Units Issued (in shares)				13,742,000				38,037				39,111
Average Unit Price (in usd per share)				$ 52.16				$ 53.03				$ 62.15