Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Distributions in Excess of Retained Earnings)	Total Shareholders’ Equity	Non-controlling Interests in Operating Partnership	Preferred Stock	Preferred Stock Preferred Stock	Preferred Stock Additional Paid-In Capital	Preferred Stock Total Shareholders’ Equity	Common Stock	Common Stock Common Stock	Common Stock Additional Paid-In Capital	Common Stock Total Shareholders’ Equity
Balance at beginning of year at Dec. 31, 2014	$ 785,201	$ 84	$ 861	$ 888,191	$ (1,746)	$ (107,779)	$ 779,611	$ 5,590
Balance (in shares) at Dec. 31, 2014		8,400,000	86,149,720
Changes in equity
Common stock redemption of common units			$ 3	1,919			1,922	(1,922)
Common stock redemption of common units (in shares)			268,947
Dividends paid	(57,602)					(57,293)	(57,293)	(309)
Equity-based compensation	4,753		$ 4	4,713			4,717	36
Equity-based compensation (in shares)			411,239
Other	(763)			(763)			(763)
Other (in shares)			(36,385)
Other comprehensive income (loss)	81				80		80	1
Net income	125,256					124,437	124,437	819
Balance at end of year at Dec. 31, 2015	$ 856,926	$ 84	$ 868	894,060	(1,666)	(40,635)	852,711	4,215
Balance (in shares) at Dec. 31, 2015		8,400,000	86,793,521
Changes in equity
Sale of stock									$ 72,290	$ 30	$ 72,260	$ 72,290	$ 89,057	$ 62	$ 88,995	$ 89,057
Sale of stock (in shares)	6,151,514									3,000,000				6,151,514
Redemption of preferred stock	$ (50,000)	$ (20)		(47,855)		(2,125)	(50,000)
Redemption of preferred stock (in shares)		(2,000,000)
Common stock redemption of common units			$ 1	1,022			1,023	(1,023)
Common stock redemption of common units (in shares)	119,308		119,308
Dividends paid	$ (66,713)					(66,467)	(66,467)	(246)
Equity-based compensation	4,221		$ 5	4,194			4,199	22
Equity-based compensation (in shares)			522,748
Other	(1,265)		$ (1)	(1,264)			(1,265)
Other (in shares)			(61,622)
Other comprehensive income (loss)	693				689		689	4
Net income	108,261					107,805	107,805	456
Balance at end of year at Dec. 31, 2016	$ 1,013,470	$ 94	$ 935	1,011,412	(977)	(1,422)	1,010,042	3,428
Balance (in shares) at Dec. 31, 2016		9,400,000	93,525,469
Changes in equity
Sale of stock									$ 154,732	$ 64	$ 154,668	$ 154,732	$ 163,575	$ 104	$ 163,471	$ 163,575
Sale of stock (in shares)	10,350,000									6,400,000				10,350,000
Redemption of preferred stock	$ (75,025)	$ (30)		(72,423)		(2,572)	(75,025)
Redemption of preferred stock (in shares)		(3,000,000)
Common stock redemption of common units			$ 1	650			651	(651)
Common stock redemption of common units (in shares)	73,322		73,322
Dividends paid	$ (86,260)					(86,019)	(86,019)	(241)
Equity-based compensation	5,887		$ 4	5,861			5,865	22
Equity-based compensation (in shares)			397,448
Other	(961)		$ (1)	(960)			(961)
Other (in shares)			(59,111)
Other comprehensive income (loss)	2,437				2,428		2,428	9
Net income	99,521					99,214	99,214	307
Balance at end of year at Dec. 31, 2017	$ 1,277,376	$ 128	$ 1,043	$ 1,262,679	$ 1,451	$ 9,201	$ 1,274,502	$ 2,874
Balance (in shares) at Dec. 31, 2017		12,800,000	104,287,128