CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Noncontrolling Interest
Common Stock, Shares, Outstanding		44,803,603
Treasury Stock, Shares	3,187,253
Beginning Balances at Dec. 31, 2016	$ 562,100	$ 44,800	$ 553,000	$ 12,600	$ (49,800)	$ 1,500
Net income	52,300	0	0	50,300	0
Proceeds from Issuance of Common Stock	0
Distributions to noncontrolling interests	(2,100)	0	0	0	0	2,100
Issuances of common stock, Value	0	0	(5,300)	0	(5,300)	0
Shares withheld for payroll taxes, Value	(1,000)	0	0	0	1,000	0
Treasury Stock, Retired, Cost Method, Amount	0	(2,900)	(35,000)	(6,600)	44,500	0
Stock-based compensation expense	6,500	0	6,500	0	0	0
Settlement of equity awards	(12,800)	0	(12,800)	0	0	0
Stock Issued During Period, Value, Treasury Stock Reissued	(600)	0	(400)	0	(1,000)	0
Ending Balances at Dec. 31, 2017	$ 605,600	$ 41,900	506,000	56,300	0	1,400
Issuances of common stock under employee benefit plans, Shares	(335,261)
Stock Issued During Period, Shares, Treasury Stock Reissued	(63,195)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	75,870
Treasury Stock, Shares, Retired		(2,864,667)
Common Stock, Shares, Outstanding		41,938,936
Net income	$ 70,000	$ 0	0	68,800	0
Proceeds from Issuance of Common Stock	0
Distributions to noncontrolling interests	(1,400)	0	0	0	0	1,400
Issuances of common stock, Value	0	0	0	0	0	0
Stock-based compensation expense	300	0	300	0	0	0
Ending Balances at Sep. 30, 2018	674,500	$ 41,900	506,300	125,100	0	1,200
Issuances of common stock under employee benefit plans, Shares		(467)
Common Stock, Shares, Outstanding		41,939,403
Net income	36,300	$ 0	0	33,000	0
Proceeds from Issuance of Common Stock	100,700	6,000	94,700	0	0	0
Distributions to noncontrolling interests	(3,900)	0	0	0	0	3,900
Issuances of common stock, Value	0	(100)	100	0	0	0
Stock-based compensation expense	1,300	0	1,300	0	0	0
Ending Balances at Sep. 30, 2019	$ 808,900	$ 48,000	$ 602,200	$ 158,100	$ 0	$ 600
Issuances of common stock under employee benefit plans, Shares		(20,463)
Shares Issued During Period, New Issues		6,037,500
Common Stock, Shares, Outstanding		47,997,366