Derivative and Other Fair Value Instruments - Summary of Fair Value Measurements for Each Major Category of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Fair Value Of SERP Investments	$ 142,075	$ 134,088
Assets, Fair Value Disclosure	142,740	136,088
Other Liabilities, Fair Value Disclosure	142,075	134,088
Liabilities, Fair Value Disclosure	166,033	146,216
Redeemable Noncontrolling Interests - Operating Partnership/Redeemable Limited Partners	432,562	379,106	$ 354,567	$ 366,955
Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	1,022	2,277
Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	665	2,000
Other Liabilities, Forward Starting Swaps	22,936	9,851
Fair Value, Inputs, Level 1 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of SERP Investments	142,075	134,088
Assets, Fair Value Disclosure	142,075	134,088
Other Liabilities, Fair Value Disclosure	142,075	134,088
Liabilities, Fair Value Disclosure	142,075	134,088
Redeemable Noncontrolling Interests - Operating Partnership/Redeemable Limited Partners	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	0	0
Other Liabilities, Forward Starting Swaps	0	0
Fair Value, Inputs, Level 2 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of SERP Investments	0	0
Assets, Fair Value Disclosure	665	2,000
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	23,958	12,128
Redeemable Noncontrolling Interests - Operating Partnership/Redeemable Limited Partners	432,562	379,106
Fair Value, Inputs, Level 2 [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	1,022	2,277
Fair Value, Inputs, Level 2 [Member] | Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	665	2,000
Other Liabilities, Forward Starting Swaps	22,936	9,851
Fair Value, Inputs, Level 3 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of SERP Investments	0	0
Assets, Fair Value Disclosure	0	0
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	0
Redeemable Noncontrolling Interests - Operating Partnership/Redeemable Limited Partners	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	0	0
Other Liabilities, Forward Starting Swaps	$ 0	$ 0