Equity (Details 2) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	280,000,000		280,000,000
Preferred stock, shares authorized (in shares)	50,000,000		50,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	66,949
Common stock issued through the dividend reinvestment plan (in shares)	602	566
Number of shares of stock grants withheld (in shares)	75,195	67,609
Stock issued during period, shares, share-based compensation, forfeited (in shares)	616
Issuance of common stock, net	$ 155,561,000	$ 0
Continuous Equity Program CEP IV
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues	755,054
Maximum value of shares of common stock that can be sold (in dollars)	$ 1,000,000,000
Shares Issued, Weighted Average Price Per Share	$ 198.26
Issuance of common stock, net	$ 147,450,000
Common stock value, remaining to be authorized under continuous equity program	$ 696,895,000
Maximum | Continuous Equity Program CEP IV
Class of Stock [Line Items]
Percentage of compensation received by sales agent	2.00%
Restricted Stock and Restricted Stock Converted From Performance Shares
Class of Stock [Line Items]
Equity instruments granted (in shares)	148,004	182,998