Condensed Statements of Comprehensive Income (Parenthetical) (unaudited) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Tax effect of the unrealized gain on short-term investment securities and cash and cash equivalents	$ 5	$ 29	$ 59	$ 67
Interest rate derivative loss reclassified into earnings, tax	$ 15	$ 19	$ 39	$ 46

Other Comprehensive Income (Loss), Securities, Available-for-Sale, Cash And Cash Equivalents Unrealized Holding Gain (Loss) Arising During Period, Tax

No definition available.

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Namespace Prefix:	save_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration