Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Stockholders' Equity
Beginning balance	$ 735,618			$ 735,618	$ 684,928
Merger-related adjustments		$ 0	$ 0	5,670	0
Total other comprehensive income		959	2,290	13,141	4,149
Ending balance		827,798	701,450	827,798	701,450
Cash flow hedge
Increase (Decrease) in Stockholders' Equity
Beginning balance	1,197	9,374	(936)	1,197	(1,678)
Gain recognized in other comprehensive income, net of tax provision of $345, $247, $1,234 and $290, respectively		1,298	931	3,349	1,104
(Gain) loss reclassified from accumulated other comprehensive loss to interest expense, net of tax provision (benefit) of $90, $(108), $37 and $(414), respectively (1)		(339)	200	117	769
Merger-related adjustments		0	0	5,670	0
Total other comprehensive income		959	1,131	9,136	1,873
Ending balance		10,333	195	10,333	195
Gain recognized in other comprehensive income, tax		345	247	1,234	290
Loss reclassified from accumulated other comprehensive loss, tax		90	(108)	37	(414)
Adjustments related to TCJA				(300)
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Beginning balance	(41,431)			(41,431)	(34,038)
Merger-related adjustments				(5,700)
Ending balance		0	(33,879)	0	(33,879)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity
Beginning balance	1,197			1,197	(1,678)
Merger-related adjustments				5,670
Ending balance		$ 10,333	$ 195	$ 10,333	$ 195
Adjustments related to TCJA	$ (300)