Accounts Receivable Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2016

Accounts Receivable, Net [Abstract]

Schedule of Accounts, Notes, Loans and Financing Receivable

Accounts receivable consisted of the following at December 31, 2016 and 2015 (dollars in thousands):

	2016			2015
Accounts receivable - trade	$	353,347		$	339,100
Accounts receivable - grants from outside parties	10,652			22,997
Accounts receivable - insurance and other third-party claims	11,994			26,574
Total accounts receivable	375,993			388,671
Allowance for doubtful accounts	(12,070		)	(6,213		)
Accounts receivable, net	$	363,923		$	382,458

Schedule of Allowance for Doubtful Accounts

Activity in the Company's allowance for doubtful accounts for the years ended December 31, 2016, 2015 and 2014 was as follows (dollars in thousands):

	2016			2015			2014
Balance, beginning of year	$	6,213		$	5,826		$	3,755
Provisions	19,655			7,512			5,191
Charges	(13,798		)	(7,125		)	(3,120		)
Balance, end of year	$	12,070		$	6,213		$	5,826