Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Measurement [Abstract]

Fair Value Assets Recurring and Nonrecurring

		March 31, 2019					December 31, 2018
	Category		Carrying amount		Fair value		Carrying amount		Fair value
Fair values disclosed:
Cash and cash equivalents	Level 1	$	266,491	$	266,491	$	237,744	$	237,744
Restricted cash	Level 1		56,743		56,743		67,823		67,823
Short-term debt	Level 2		8,687		8,687		19,896		19,896
Long-term debt
Senior unsecured notes	Level 1		489,579		510,938		489,136		487,813
Term loans	Level 2		213,758		215,879		222,162		224,582