Trade Accounts Receivable, Net (Tables)

12 Months Ended

Dec. 31, 2017

Summary of trade accounts receivables

At December 31 this account comprises:

	2016					2017
	Current			Non-current		Current			Non-current
Invoices receivable		903,878			652,939		459,721			819,699
Collection rights		150,065			14,580		546,351			28,891
		1,053,943			667,519		1,006,072			848,590
Impairment of receivables		(22,673	)		—		(13,348	)		—
		1,031,270			667,519		992,724			848,590

Summary of aging of trade accounts receivable

Aging of trade accounts receivable is as follows:

	At December 31,
	2016		2017
Current		1,396,040		1,575,709
Past due up to 30 days		103,617		118,158
Past due from 31 days up to 180 days		113,825		141,121
Past due from 181 days up to 360 days		29,506		1,962
Past due over 360 days		78,474		17,712
		1,721,462		1,854,662