Common Stock and Other Equity Related Transactions - Employee Stock Purchase Program (Details) - USD ($)													12 Months Ended
	Jan. 12, 2018	Oct. 13, 2017	Jul. 14, 2017	Apr. 14, 2017	Jan. 13, 2017	Oct. 14, 2016	Jul. 08, 2016	Apr. 08, 2016	Jan. 08, 2016	Oct. 09, 2015	Jul. 10, 2015	Apr. 10, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Stock Purchase Program [Line Items]
ESPP, purchase price discount (in percentage)													85.00%
ESPP, issued during the period (in shares)													24,715	17,037	19,788
Disclosure Regular Quarterly Distributions Declared And Paid To Common Stockholders And Common O P Unit Non Controlling Interests [Abstract]
Distribution Amount Per Share (usd per share)		$ 0.487500	$ 0.487500	$ 0.487500	$ 0.425000	$ 0.425000	$ 0.425000	$ 0.425000	$ 0.375000	$ 0.375000	$ 0.375000	$ 0.375000
Employee Stock Purchase Plan
Employee Stock Purchase Program [Line Items]
Amendment Date													May 10, 2016
Maximum
Employee Stock Purchase Program [Line Items]
ESPP authorized amount													$ 250,000
Number of shares authorized ESPP (in shares)													2,000,000
Subsequent Event
Disclosure Regular Quarterly Distributions Declared And Paid To Common Stockholders And Common O P Unit Non Controlling Interests [Abstract]
Distribution Amount Per Share (usd per share)	$ 0.4875