Schedule III - Real Estate and Accumulated Depreciation - Activity in Real Estate Facilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real estate, gross:
Balance at end of year	$ 8,192,491
Accumulated depreciation:
Balance at beginning of year	900,861
Balance at end of year	1,060,060	$ 900,861
Net real estate assets:
Net real estate assets	7,132,431	6,770,447	$ 5,689,309
Aggregate cost of real estate for U.S. federal income tax purposes	6,914,712
Operating facilities
Real estate, gross:
Balance at beginning of year	7,649,448	6,392,487	4,722,162
Acquisitions	628,391	1,159,304	1,609,608
Improvements	71,090	92,480	46,696
Transfers from construction in progress (to operating facilities)	19,079	26,400	19,971
Dispositions and other	209,267	21,223	5,950
Balance at end of year	8,158,741	7,649,448	6,392,487
Accumulated depreciation:
Balance at beginning of year	900,861	728,087	604,336
Depreciation expense	185,903	174,906	123,751
Dispositions and other	26,704	2,132	0
Balance at end of year	1,060,060	900,861	728,087
Real estate under development/redevelopment:
Real estate, gross:
Balance at beginning of year	21,860	24,909	17,870
Current development	33,484	23,404	27,010
Transfers from construction in progress (to operating facilities)	(19,079)	(26,400)	(19,971)
Dispositions and other	2,515	53	0
Balance at end of year	$ 33,750	$ 21,860	$ 24,909