Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance (in shares)	48,065
Balance	$ 730,157	$ 699,221
Net loss	(7,640)	(762)
Issuance of common stock	3,179	636
Repurchase of common stock	(2,074)	(1,239)
Dividends paid on common stock	$ (9,493)	$ (9,003)
Dividends paid on common stock (in dollars per share)	$ 0.1975	$ 0.1875
Balance (in shares)	48,134
Balance	$ 714,129	$ 688,853
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance (in shares)	48,065	48,012
Balance	$ 481	$ 480
Issuance of common stock (in shares)	109	95
Issuance of common stock	$ 0	$ 1
Repurchase of common stock (in shares)	(40)	(33)
Balance (in shares)	48,134	48,074
Balance	$ 481	$ 481
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	337,623	336,229
Issuance of common stock	3,179	635
Repurchase of common stock	(2,074)	(1,239)
Balance	338,728	335,625
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	392,053	362,512
Net loss	(7,640)	(762)
Dividends paid on common stock	(9,493)	(9,003)
Balance	$ 374,920	$ 352,747