Related Party Transactions (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) nonemployeedirectors shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($)	May 23, 2018 shares
Related Party Transaction [Line Items]
Number Of Non Employee Directors Electing To Receive Deferred Stock Units | nonemployeedirectors	4
Shares issued | shares	154,537,378	154,404,186		36,836
Deferred Stock Units Outstanding	74,966	105,479
Brother of Senior Executive Vice President [Member]
Related Party Transaction [Line Items]
Aggregate leasing commissions paid to related parties | $	$ 921,000	$ 368,000	$ 374,000