Basis and Summary of Significant Accounting Policies - Changes in Accumulated Other Comprehensive (Loss) Income by Component (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive (Loss) Income [Line Items]
Reclassification out of accumulated other comprehensive (loss) income			$ 0
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			1,481,598,000
Other Comprehensive Income	$ 446,000	$ 93,000	649,000	$ 686,000
Ending balance	1,542,073,000		1,542,073,000
Foreign Currency
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(531,000)
Other Comprehensive Income			649,000
Ending balance	$ 118,000		$ 118,000