Accounts Receivable Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2015

Accounts Receivable, Net [Abstract]

Schedule of Accounts, Notes, Loans and Financing Receivable

Accounts receivable consisted of the following at December 31, 2015 and 2014 (dollars in thousands):

	2015			2014
Accounts receivable - trade	$	339,100		$	304,087
Accounts receivable - grants from outside parties	22,997			32,076
Accounts receivable - insurance and other third-party claims	26,574			26,941
Total accounts receivable	388,671			363,104
Allowance for doubtful accounts	(6,213		)	(5,826		)
Accounts receivable, net	$	382,458		$	357,278

Schedule of Allowance for Doubtful Accounts

Activity in the Company's allowance for doubtful accounts for the years ended December 31, 2015, 2014 and 2013 was as follows (dollars in thousands):

	2015			2014			2013
Balance, beginning of year	$	5,826		$	3,755		$	2,693
Provisions	7,512			5,191			2,741
Charges	(7,125		)	(3,120		)	(1,679		)
Balance, end of year	$	6,213		$	5,826		$	3,755