CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance at Dec. 31, 2016	$ 2,248,724	$ 1,915	$ 1,042,696	$ 2,116,341	$ (1,134)	$ (911,094)
Beginning Balance (in shares) at Dec. 31, 2016		191,526,000
Net income (loss)	5,910			5,910
Foreign currency translation adjustment	7,956				7,956
Equity offering	471,570	$ 182	471,388
Equity offering (in shares)		18,170,000
Shares issued for acquisitions	1,226,890	$ 551	1,226,339
Shares issued for acquisitions (in shares)		55,097,000
Issuance of restricted stock		$ 9	(9)
Issuance of restricted stock (in shares)		891,000
Vesting of restricted stock units		$ 5	(5)
Vesting of restricted stock units (in shares)		549,000
Forfeitures of restricted stock (in shares)		(24,000)
Exercise of stock options	931		931
Exercise of stock options (in shares)		50,000
Stock-based compensation	44,483		44,483
Payment of cash dividends	(16,315)			(16,315)
Dividend equivalents	(39)			(39)
Purchase of treasury stock	(7,617)					(7,617)
Ending Balance at Dec. 31, 2017	3,982,493	$ 2,662	2,785,823	2,105,897	6,822	(918,711)
Ending Balance (in shares) at Dec. 31, 2017		266,259,000
Net income (loss)	(321,421)			(321,421)
Foreign currency translation adjustment	(4,335)				(4,335)
Restricted stock issued for acquisition	2,932	$ 2	2,930
Restricted stock issued for acquisition (in shares)		192,000
Issuance of restricted stock		$ 4	(4)
Issuance of restricted stock (in shares)		381,000
Vesting of restricted stock units		$ 5	(5)
Vesting of restricted stock units (in shares)		452,000
Forfeitures of restricted stock (in shares)		(8,000)
Exercise of stock options	485		485
Exercise of stock options (in shares)		40,000
Stock-based compensation	37,925		37,925
Payment of cash dividends	(30,589)			(30,589)
Dividend equivalents	(330)			(330)
Purchase of treasury stock	(161,737)					(161,737)
Ending Balance at Dec. 31, 2018	$ 3,505,423	$ 2,673	2,827,154	1,753,557	2,487	(1,080,448)
Ending Balance (in shares) at Dec. 31, 2018	267,315,526	267,316,000
Net income (loss)	$ (425,703)			(425,703)
Foreign currency translation adjustment	2,991				2,991
Issuance of restricted stock		$ 2	(2)
Issuance of restricted stock (in shares)		185,000
Vesting of restricted stock units		$ 12	(12)
Vesting of restricted stock units (in shares)		1,173,000
Forfeitures of restricted stock (in shares)		(2,000)
Exercise of stock options	$ 9,219	$ 7	9,212
Exercise of stock options (in shares)	700,000	700,000
Stock-based compensation	$ 39,328		39,328
Payment of cash dividends	(32,428)			(32,428)
Dividend equivalents	(524)			(524)
Purchase of treasury stock	(264,686)					(264,686)
Ending Balance at Dec. 31, 2019	$ 2,833,620	$ 2,694	$ 2,875,680	$ 1,294,902	$ 5,478	$ (1,345,134)
Ending Balance (in shares) at Dec. 31, 2019	269,372,257	269,372,000