Summary of Significant Accounting Policies Cash, Cash Equivalent, and Restricted Cash (Tables)

12 Months Ended

Dec. 31, 2017

Cash and Cash Equivalents [Abstract]

Restrictions on Cash and Cash Equivalents [Table Text Block]

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Consolidated Statements of Cash Flows:

	Year Ended December 31,
	2017		2016		2015
	(in thousands)
Cash and cash equivalents	$	176,274	$	133,565	$	131,018
Current restricted cash included in other current assets	51		—		—
Long-term restricted cash	311,010		—		—
Total cash, cash equivalents, and restricted cash:	$	487,335	$	133,565	$	131,018