Verizon Merger Agreement (Details) - USD ($)			12 Months Ended
	May 11, 2017	Apr. 09, 2017	Jul. 31, 2017	Aug. 02, 2017
Verizon Merger Agreement (Textual)
Nonassessable shares of common stock, value	$ 184.00
Merger consideration, description	Five (5)-day volume-weighted average per share price ending on the second full trading day prior to the Effective Time, rounded to two decimal points, of Verizon Shares on the New York Stock Exchange (the "Verizon Share Value") and rounded to the nearest ten-thousandth of a share (collectively and in the aggregate, the "Merger Consideration").
Termination fee	$ 38,000,000	$ 38,000,000	$ 38,000,000
Parent termination fee			85,000,000
Incurred costs in merger agreement	$ 2,847,000
Payment to consent decree, percentage	20.00%
Financial advisor and legal fees	$ 63,900,000
Special meeting voting percentage		22.00%
Subsequent Event [Member]
Verizon Merger Agreement (Textual)
Special meeting voting percentage				99.00%
Verizon Merger Agreement [Member]
Verizon Merger Agreement (Textual)
Termination fee	38,000,000
Verizon merger agreement payaments	38,000,000
Repayaments of verizon merger agreement	38,000,000
Verizon Merger Agreement [Member] | Subsequent Event [Member]
Verizon Merger Agreement (Textual)
Special meeting voting percentage				89.00%
Rand [Member]
Verizon Merger Agreement (Textual)
Retention bonus payment	1,000,000
Breau [Member]
Verizon Merger Agreement (Textual)
Retention bonus payment	1,000,000
Jonas [Member]
Verizon Merger Agreement (Textual)
Retention bonus payment	1,800,000
Former SPSI CEO [Member]
Verizon Merger Agreement (Textual)
Balance owed of straight path spectrum	$ 3,000,000
Superior offer [Member]
Verizon Merger Agreement (Textual)
Termination fee			$ 38,000,000
Common Class A [Member] | Verizon Merger Agreement [Member]
Verizon Merger Agreement (Textual)
Common stock, par value	$ 0.01
Common Class B [Member] | Verizon Merger Agreement [Member]
Verizon Merger Agreement (Textual)
Common stock, par value	$ 0.01