Consolidated Statement Of Equity - USD ($)	Total	Revision of Prior Period, Accounting Standards Update, Adjustment [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Cumulative Dividends In Excess Of Net Income [Member]	Cumulative Dividends In Excess Of Net Income [Member] Revision of Prior Period, Accounting Standards Update, Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Revision of Prior Period, Accounting Standards Update, Adjustment [Member]	Parent [Member]	Parent [Member] Revision of Prior Period, Accounting Standards Update, Adjustment [Member]	Noncontrolling Interest [Member]	At-The-Market [Member] Common Stock [Member]	Convertible Debt [Member] Common Stock [Member]
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	$ (2,427,000)
Balance, shares at Dec. 31, 2017			41,532,154
Balance, value at Dec. 31, 2017	1,322,117,000		$ 415,000	$ 1,289,919,000	$ 32,605,000		$ (822,000)		$ 1,322,117,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common stockholders	154,333,000				154,333,000		1,886,000		156,219,000
Comprehensive income	156,219,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments				(2,427,000)					(2,427,000)
Stock Issued During Period, Shares, New Issues			1,112,363
Stock Issued During Period, Value, New Issues	81,784,000		$ 12,000	81,772,000					81,784,000
Payments of Stock Issuance Costs	(1,835,000)			1,835,000					1,835,000
Shares issued on stock options exercised, shares			55,894
Share-based Payment Arrangement, Noncash Expense				2,490,000
Share-based compensation	2,490,000								2,490,000
Dividends declared, $1.43 per share	(168,635,000)				(168,635,000)				(168,635,000)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0
Balance, shares at Dec. 31, 2018			42,700,411
Balance, value at Dec. 31, 2018	1,389,713,000		$ 427,000	1,369,919,000	18,068,000		1,299,000		1,389,713,000		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Retained Earnings (Accumulated Deficit)						$ (235,000)		$ 235,000
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	(643,000)										(643,000)
Net income attributable to common stockholders	160,456,000				160,456,000		(4,731,000)		155,725,000
Comprehensive income	155,718,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments	$ 95,774,000								95,774,000
Stock Issued During Period, Shares, New Issues	1,209,522											1,209,522	626,397
Stock Issued During Period, Value, New Issues	$ 38,186,000		$ 12,000	95,762,000					38,186,000
Shares issued on stock options exercised, shares			51,156
Share-based Payment Arrangement, Noncash Expense				3,646,000
Share-based compensation	3,646,000								3,646,000
Dividends declared, $1.43 per share	(183,855,000)				(183,855,000)				(183,855,000)
Distributions to noncontrolling interest	(15,000)										15,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(1,559,000)			1,559,000					(1,559,000)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(7,000)										(7,000)
Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments			$ 6,000	38,180,000
Shares issued on stock options exercised, value	$ (1,000)		$ (1,000)						(1,000)
Balance, shares at Dec. 31, 2019	44,587,486		44,587,486
Balance, value at Dec. 31, 2019	$ 1,498,252,000		$ 446,000	1,505,948,000	(5,331,000)		(3,432,000)		1,497,631,000		621,000
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	(10,791,000)										(10,791,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common stockholders	185,126,000				185,126,000		(3,717,000)		181,409,000
Comprehensive income	181,594,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments	$ 34,649,000								34,649,000
Stock Issued During Period, Shares, New Issues	535,990											535,990	626,397
Stock Issued During Period, Value, New Issues			$ 5,000	34,644,000
Share-based Payment Arrangement, Noncash Expense				3,061,000
Share-based compensation	$ 3,061,000								3,061,000
Dividends declared, $1.43 per share	(197,585,000)				(197,585,000)				(197,585,000)
Distributions to noncontrolling interest	(886,000)										886,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(2,705,000)			2,705,000					2,705,000
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	185,000										185,000
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture			62,516
Shares issued on stock options exercised, value	$ (1,000)		$ (1,000)	(2,000)					(1,000)
Balance, shares at Dec. 31, 2020	45,185,992		45,185,992
Balance, value at Dec. 31, 2020	$ 1,522,945,000		$ 452,000	$ 1,540,946,000	$ (22,015,000)		$ (7,149,000)		$ 1,512,234,000		$ 10,711,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Retained Earnings (Accumulated Deficit)		$ (4,225,000)				$ (4,225,000)				$ (4,225,000)