Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 779,906	$ 730,157
Net loss	(20,307)	(7,640)
Issuance of common stock	7,229	3,179
Repurchase of common stock	(1,373)	(2,074)
Dividends paid on common stock	$ (10,315)	$ (9,493)
Dividends paid on common stock (in dollars per share)	$ 0.2125	$ 0.1975
Balance at end of period (in shares)	48,714,000	48,532,000
Balance at end of period	$ 755,140	$ 714,129
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period (in shares)	48,532,000	48,065,000
Balance at beginning of period	$ 485	$ 481
Issuance of common stock (in shares)	210,000	109,000
Issuance of common stock	$ 2	$ 0
Repurchase of common stock (in shares)	(28,000)	(40,000)
Balance at end of period (in shares)	48,714,000	48,134,000
Balance at end of period	$ 487	$ 481
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	362,275	337,623
Issuance of common stock	7,227	3,179
Repurchase of common stock	(1,373)	(2,074)
Balance at end of period	368,129	338,728
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	417,146	392,053
Net loss	(20,307)	(7,640)
Dividends paid on common stock	(10,315)	(9,493)
Balance at end of period	$ 386,524	$ 374,920