Contract balances (Details 2) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract assets	$ 117,036		$ 104,239
Change in contract assets	12,797
Contract liabilities - current	(86,031)		(93,901)
Change in contract liabilities - current	7,870
Contract liabilities - noncurrent	(30)		(135)
Change in contract liabilities - noncurrent	105
Net contract assets	30,975		$ 10,203
Change in net contract assets	20,772
Amounts included in contract liability at the beginning of the period	56,400	$ 52,000
Amounts from performance obligations satisfied in prior periods	$ 18,700	$ 3,100

Amount of increase (decrease) in current contract assets, net

No definition available.

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- Definition

Total of net contract assets and liabilities

+ References

No definition available.

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- Definition

Amount of increase (decrease) in net contract assets and liabilities

+ References

No definition available.

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Amount of increase (decrease) in current contract liabilities

+ References

No definition available.

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- Definition

Amount of increase (decrease) in noncurrent contract liabilities

+ References

No definition available.

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- Definition

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

+ References

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-Publisher FASB
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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

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- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

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- Definition

Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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