Segments (Reconciliation of adjusted EBITDA to consolidated financial statements) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Income before income taxes		$ 46,818	$ 27,996	$ 119,451	$ 59,689
Interest expense		5,926	6,377	17,916	18,960
Interest income		(117)	0	(117)	0
Depreciation and amortization		16,626	17,625	48,560	51,996
Merger and integration costs		1,459	2,574	3,627	13,339
Non-cash stock compensation expense		3,310	1,366	8,226	4,751
Acquisition costs		0	0	267	317
Other items	[1]	346	3,359	2,447	3,385
Other reconciling items [Member] | Other reconciling items [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization		520	629	1,481	1,829
Adjusted EBITDA		18,330	10,861	52,496	36,445
Operating segments [Member] | Geographic divisions [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization		16,106	16,996	47,079	50,167
Adjusted EBITDA		$ (92,698)	$ (70,158)	$ (252,873)	$ (188,882)

[1] For the three and nine months ended September 30, 2018, the amounts represent costs incurred in connection with the departure of the Company’s former chief executive officer and the search for and appointment of his permanent replacement. For the three and nine months ended September 30, 2017, the amounts represent asset impairment charges related to real estate held for sale and expense incurred related to pending litigation.