GBG Acquisition - Allocation and Proforma (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Oct. 29, 2018	Dec. 31, 2016
Intangible assets and liabilities acquired:
Goodwill	$ 376,132	$ 8,380		$ 8,271
GBG and its subsidiaries
Business Acquisition
Inventory adjustment to fair value	32,400
Assets acquired and liabilities assumed:
Accounts receivable			$ 65,106
Inventories			371,605
Prepaid expenses and other current assets			56,380
Property and equipment			86,971
Other assets			41
Accounts payable and accrued expenses			(589,849)
Intangible assets and liabilities acquired:
Preliminary purchase price			1,179,669
Unaudited pro forma results
Net sales	2,302,195	2,244,604
Cost of goods sold	1,785,871	1,691,199
Gross margin	$ 516,324	$ 553,405
Gross margin % of net sales	22.40%	24.70%
Operating expenses
Selling, general and administrative	$ 569,726	$ 423,392
Depreciation and amortization	90,241	92,554
Total operating expenses	659,967	515,946
Operating (loss) income	(143,643)	37,459
Interest expense	156,329	152,082
Gain on contingent consideration	(17,675)	(18,687)
Loss before income taxes	(282,297)	(95,936)
Income tax benefit	5,927	5,331
Net loss	$ (276,370)	$ (90,605)
Loss per common share - basic (in dollars per share)	$ (4.75)	$ (1.58)
Loss per common share - diluted (in dollars per share)	$ (4.75)	$ (1.58)
Weighted average shares outstanding basic and diluted (in shares)	58,143	57,516
Cost of goods sold | GBG and its subsidiaries
Business Acquisition
Inventory adjustment to fair value	$ 23,600
Selling, general and administrative expenses | GBG and its subsidiaries
Business Acquisition
Amortization expense	$ 39,800
Goodwill | GBG and its subsidiaries
Intangible assets and liabilities acquired:
Goodwill			367,725
Leasehold interests | GBG and its subsidiaries
Intangible assets and liabilities acquired:
Leasehold interests			(2,310)
Customer relationships | GBG and its subsidiaries
Intangible assets and liabilities acquired:
Customer relationships			$ 824,000