Long-Term Debt - Net Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Debt Disclosure [Abstract]
Interest expense	$ 13,044	$ 8,409
Interest income	(444)	(650)
Capitalized interest	(1,916)	(3,689)
Net interest expense	$ 10,684	$ 4,070