Revenue Recognition (Tables)

6 Months Ended

Jun. 30, 2018

Revenues [Abstract]

Contract with Customer, Asset and Liability

A summary of significant net changes in the contract assets and the contract liabilities balances during the period is as follows:

	2018
	Contract liabilities, less contract assets
	(in thousands)
Beginning balance, January 1	$	59,808
Changes due to business combination	38,816
Revenues recognized from beginning contract liability	(30,045		)
Increases due to amounts collected or due	137,882
Revenues recognized from current period increases	(75,618		)
Other	(2,687		)
Ending balance, June 30	$	128,156