Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended			52 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Class Of Stock [Line Items]
Redeemable noncontrolling interest in joint venture	5.00%
Aggregate proceeds received from offering	$ 42,554	$ 588,704	$ 572,324	$ 1,700,000
Maximum percentage on selling commission, marketing support fees, and other organizational and offering cost on aggregate gross offering proceeds	15.00%
Stock issuance and other offering cost		57,400	59,800
Cash distribution declared	$ 74,008	63,201	31,919
Cash paid to stockholders	$ 31,454	$ 26,373	$ 14,203
Stock distributions, shares		3,200	2,400
Redemption of common stock, per share	$ 9.73	$ 9.51	$ 9.24
Redemptions of common stock	$ 36,243	$ 9,309	$ 2,996
Common Stock
Class Of Stock [Line Items]
Aggregate proceeds received from offering	$ 44	$ 561	$ 560
Subscriptions received for common stock through public offering and reinvestment plan (in shares)	4,365	55,956	56,006
Stock distributions, shares		3,196	2,356
Redemption of common stock, shares	3,725	978	324
Redemptions of common stock	$ 37	$ 12	$ 3
Reinvestment Plan
Class Of Stock [Line Items]
Aggregate proceeds received from offering	$ 42,600	$ 36,800	$ 17,700
Subscriptions received for common stock through public offering and reinvestment plan (in shares)	4,400	3,700	1,800
Cash distribution declared	$ 42,600	$ 36,800	$ 17,700