Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2018

Revenues [Abstract]

Contract with Customer, Asset and Liability [Table Text Block]

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
Revenue recognized from beginning contract liability	(24,549		)
Revenue recognized from current period increases	(6,352		)
Increases due to amounts collected or due	56,051
Other	(1,243		)
Ending balance, March 31	$	122,531