Condensed Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period Of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Distributions in Excess of Accumulated Earnings	Distributions in Excess of Accumulated Earnings Cumulative Effect, Period Of Adoption, Adjustment	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Cumulative Effect, Period Of Adoption, Adjustment	Noncontrolling Interest	Noncontrolling Interest Cumulative Effect, Period Of Adoption, Adjustment
Issuance of common stock under:
Cumulative effect upon adoption of ASU No. 2016-13	$ 6,393,844	$ 181	$ 7	$ 7,093,079	$ (812,796)		$ (13,217)	$ 175	$ 126,771	$ 6
Balance at period beginning (in shares) at Dec. 31, 2018			65,890,000
Balance at period beginning at Dec. 31, 2018	6,393,844	181	$ 7	7,093,079	(812,796)		(13,217)	175	126,771	6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	329,266				310,468				18,798
Reversal of unrealized gains upon the sale of marketable debt securities	(32)						(31)		(1)
Change in fair value of derivatives and amortization of swap settlements	(6,366)						(6,152)		(214)
Change in fair value of marketable debt securities, net	203						197		6
Issuance of common stock under:
Stock option and restricted stock plans, net (in shares)			188,000
Stock option and restricted stock plans, net	32,907			32,907
Sale of common stock, net (in shares)			228,000
Sale of common stock, net	72,549			72,549
Equity based compensation costs	7,914			7,016					898
Retirement of common stock, net (in shares)			(234,000)
Retirement of common stock, net	(56,989)		$ 0	(56,989)
Cumulative effect upon adoption of ASU No. 2016-13	6,393,844	181	$ 7	7,093,079	(812,796)		(19,028)	$ 175	189,904	$ 6
Changes in the redemption value of redeemable noncontrolling interest	(3,675)			(5,048)					1,373
Changes in noncontrolling interest from acquisition	65,472								65,472
Distributions to noncontrolling interest	(20,897)								(20,897)
Redemptions of noncontrolling interest (in shares)			10,000
Redemptions	(14,180)			(11,872)					(2,308)
Common stock dividends	(385,193)				(385,193)
Balance at period end (in shares) at Sep. 30, 2019			66,082,000
Balance at period end at Sep. 30, 2019	$ 6,415,004		$ 7	7,131,642	(887,521)		(19,028)		189,904
Issuance of common stock under:
Common stock dividends (in dollars per share)	$ 5.85
Accounting standards update [Extensible List]	us-gaap:AccountingStandardsUpdate201712Member
Cumulative effect upon adoption of ASU No. 2016-13	$ 6,345,116		$ 7	7,031,886	(857,994)		(18,992)		190,209
Balance at period beginning (in shares) at Jun. 30, 2019			65,727,000
Balance at period beginning at Jun. 30, 2019	6,345,116		$ 7	7,031,886	(857,994)		(18,992)		190,209
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	105,700				99,335				6,365
Change in fair value of derivatives and amortization of swap settlements	(12)						(12)
Change in fair value of marketable debt securities, net	(25)						(24)		(1)
Issuance of common stock under:
Stock option and restricted stock plans, net (in shares)			126,000
Stock option and restricted stock plans, net	27,679			27,679
Sale of common stock, net (in shares)			228,000
Sale of common stock, net	72,631			72,631
Equity based compensation costs	1,814			1,544					270
Cumulative effect upon adoption of ASU No. 2016-13	6,415,004		$ 7	7,131,642	(887,521)		(19,028)		189,904
Changes in the redemption value of redeemable noncontrolling interest	(2,247)			(2,309)					62
Distributions to noncontrolling interest	(6,789)								(6,789)
Redemptions of noncontrolling interest (in shares)			1,000
Redemptions	(1)			211					(212)
Common stock dividends	(128,862)				(128,862)
Balance at period end (in shares) at Sep. 30, 2019			66,082,000
Balance at period end at Sep. 30, 2019	$ 6,415,004		$ 7	7,131,642	(887,521)		(19,028)		189,904
Issuance of common stock under:
Common stock dividends (in dollars per share)	$ 1.95
Cumulative effect upon adoption of ASU No. 2016-13	$ 6,415,004		7	7,131,642	(887,521)		(19,028)		189,904
Cumulative effect upon adoption of ASU No. 2016-13	6,403,504	(190)	$ 7	7,121,927	(887,619)	$ (190)	(13,888)		183,077
Balance at period beginning (in shares) at Dec. 31, 2019			66,092,000
Balance at period beginning at Dec. 31, 2019	6,403,504	(190)	$ 7	7,121,927	(887,619)	(190)	(13,888)		183,077
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	497,683				473,125				24,558
Cash flow hedge losses reclassified to earnings	3,282						3,171		111
Change in fair value of derivatives and amortization of swap settlements	(6,119)						(5,911)		(208)
Change in fair value of marketable debt securities, net	(178)						(172)		(6)
Issuance of common stock under:
Stock option and restricted stock plans, net (in shares)			95,000
Stock option and restricted stock plans, net	9,201			9,201
Sale of common stock, net	(228)			(228)
Equity based compensation costs	9,294			8,956					338
Retirement of common stock, net (in shares)			(985,000)
Retirement of common stock, net	(222,990)			(222,990)
Cumulative effect upon adoption of ASU No. 2016-13	6,267,482	$ (190)	$ 7	6,921,631	(821,841)	$ (190)	(16,800)		183,077
Changes in the redemption value of redeemable noncontrolling interest	6,691			6,888					(197)
Changes in noncontrolling interest from acquisition	1,349								1,349
Distributions to noncontrolling interest	(23,689)								(23,689)
Redemptions of noncontrolling interest (in shares)			8,000
Redemptions	(2,971)			(2,123)					(848)
Common stock dividends	(407,157)				(407,157)
Balance at period end (in shares) at Sep. 30, 2020			65,210,000
Balance at period end at Sep. 30, 2020	$ 6,267,482		$ 7	6,921,631	(821,841)		(16,800)		184,485
Issuance of common stock under:
Common stock dividends (in dollars per share)	$ 6.2325
Accounting standards update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Cumulative effect upon adoption of ASU No. 2016-13	$ 6,352,881		$ 7	6,944,805	(760,028)		(18,710)		186,807
Balance at period beginning (in shares) at Jun. 30, 2020			65,331,000
Balance at period beginning at Jun. 30, 2020	6,352,881		$ 7	6,944,805	(760,028)		(18,710)		186,807
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	78,842				73,661				5,181
Change in fair value of derivatives and amortization of swap settlements	1,884						1,821		63
Change in fair value of marketable debt securities, net	92						89		3
Issuance of common stock under:
Sale of common stock, net	(95)			(95)
Equity based compensation costs	2,361			2,279					82
Retirement of common stock, net (in shares)			(121,000)
Retirement of common stock, net	(26,586)		$ 0	(26,586)
Cumulative effect upon adoption of ASU No. 2016-13	6,267,482		$ 7	6,921,631	(821,841)		(16,800)		184,485
Changes in the redemption value of redeemable noncontrolling interest	2,522			2,346					176
Distributions to noncontrolling interest	(7,677)								(7,677)
Redemptions of noncontrolling interest (in shares)			0
Redemptions	(1,268)			(1,118)					(150)
Common stock dividends	(135,474)				(135,474)
Balance at period end (in shares) at Sep. 30, 2020			65,210,000
Balance at period end at Sep. 30, 2020	$ 6,267,482		$ 7	6,921,631	(821,841)		(16,800)		184,485
Issuance of common stock under:
Common stock dividends (in dollars per share)	$ 2.0775
Cumulative effect upon adoption of ASU No. 2016-13	$ 6,267,482		$ 7	$ 6,921,631	$ (821,841)		$ (16,800)		$ 184,485