Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

Revenue from Contracts with Customers (Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
ASSETS
Total assets	$ 6,319,618		$ 6,678,715
Accounts receivable (net of allowance of $15,889 and $15,985, respectively)	488,028		524,424
Current income taxes	42,274		58,439
Other current assets and prepayments	94,227		77,954
Noncurrent income taxes	61,367		59,909
Other assets	531,225		540,796
Total Liabilities
Total liabilities	6,104,725		6,490,154
Accounts payable and accrued liabilities	1,375,166		1,486,741
Current income taxes	9,457		8,823
Advance billings	292,174		288,372
Deferred taxes on income	239,472		234,643
Other noncurrent liabilities	499,794		524,689
Stockholders’ equity:
Total stockholders’ equity	214,893		188,561	$ (46,338)	$ (103,660)
Retained earnings	5,235,874		5,229,584
Accumulated other comprehensive loss	(771,995)		$ (792,173)
ASC 606
ASSETS
Total assets	6,319,618
Accounts receivable (net of allowance of $15,889 and $15,985, respectively)	488,028
Current income taxes	42,274
Other current assets and prepayments	94,227
Noncurrent income taxes	61,367
Other assets	531,225
Total Liabilities
Total liabilities	6,104,725
Accounts payable and accrued liabilities	1,375,166
Current income taxes	9,457
Advance billings	292,174
Deferred taxes on income	239,472
Other noncurrent liabilities	499,794
Stockholders’ equity:
Total stockholders’ equity	214,893
Retained earnings	5,235,874	$ (9,000)
Accumulated other comprehensive loss	(771,995)
Pro forma \| ASC 606
ASSETS
Total assets	6,331,186
Accounts receivable (net of allowance of $15,889 and $15,985, respectively)	486,327
Current income taxes	42,472
Other current assets and prepayments	97,909
Noncurrent income taxes	61,571
Other assets	540,410
Total Liabilities
Total liabilities	6,115,357
Accounts payable and accrued liabilities	1,373,465
Current income taxes	6,034
Advance billings	302,586
Deferred taxes on income	243,843
Other noncurrent liabilities	500,767
Stockholders’ equity:
Total stockholders’ equity	215,829
Retained earnings	5,236,690
Accumulated other comprehensive loss	(771,875)
Total increase (decrease) \| ASC 606
ASSETS
Total assets	(11,568)
Accounts receivable (net of allowance of $15,889 and $15,985, respectively)	1,701
Current income taxes	(198)
Other current assets and prepayments	(3,682)
Noncurrent income taxes	(204)
Other assets	(9,185)
Total Liabilities
Total liabilities	(10,632)
Accounts payable and accrued liabilities	1,701
Current income taxes	3,423
Advance billings	(10,412)
Deferred taxes on income	(4,371)
Other noncurrent liabilities	(973)
Stockholders’ equity:
Total stockholders’ equity	(936)
Retained earnings	(816)
Accumulated other comprehensive loss	$ (120)