Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Measurement [Abstract]

Fair Value Assets Recurring and Nonrecurring

		September 30, 2018					December 31, 2017
	Category		Carrying amount		Fair value		Carrying amount		Fair value
Fair values disclosed:
Cash and cash equivalents	Level 1	$	228,764	$	228,764	$	267,910	$	267,910
Restricted cash	Level 1		75,281		75,281		63,206		63,206
Short-term debt	Level 2		10,532		10,532		7,018		7,018
Long-term debt
Senior unsecured notes	Level 1		488,683		498,750		487,339		520,000
Term loans	Level 2		263,095		266,036		325,553		329,687