Fair value measurement (Tables)

6 Months Ended

Jun. 30, 2020

Fair value measurement

Fair Value Assets Recurring and Nonrecurring

		June 30, 2020				December 31, 2019
		Carrying				Carrying
	Category	amount		Fair value		amount		Fair value
Fair values disclosed:
Cash and cash equivalents	Level 1	$	389,720	$	389,720	$	359,671	$	359,671
Restricted cash	Level 1		148,293		148,293		60,585		60,585
Short-term debt	Level 2		21,980		21,980		4,705		4,705
Long-term debt
Senior unsecured notes	Level 1		491,829		513,125		490,933		520,625
Term loans	Level 2		140,134		140,702		154,548		155,355