Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 52,684	$ 53,064
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,913	1,215
Amortization of debt issuance costs	61	61
Stock-based compensation	901	886
Deferred compensation	19	61
Loss on disposal of assets	62	62
Deferred income taxes	(742)	483
Effect of changes in operating assets and liabilities:
Receivables	11,913	(12,504)
Inventories	(2,749)	(6,450)
Prepaid expenses and other current assets	589	(7,663)
Accounts payable	14,907	10,485
Other liabilities	8,050	(2,160)
Net cash provided by operating activities	89,608	37,540
Cash flows from investing activities:
Capital expenditures	(3,767)	(19,704)
Net cash used in investing activities	(3,767)	(19,704)
Cash flows from financing activities:
Principal payments on long-term debt	(1,980)	(1,980)
Proceeds from exercise of stock options	43	38
Net cash used in financing activities	(1,937)	(1,942)
Net increase in cash and cash equivalents	83,904	15,894
Cash and cash equivalents at beginning of period	95,788	42,874
Cash and cash equivalents at end of period	$ 179,692	$ 58,768