Investments - Other Investments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Schedule of Investments [Line Items]
Other investments	$ 25,630	$ 34,215
Fair Value, Measurements, Recurring
Schedule of Investments [Line Items]
Other investments	25,630	34,215
Fair Value, Measurements, Recurring | Iridium [Member]
Schedule of Investments [Line Items]
Other investments	25,592	34,165
Fair Value, Measurements, Recurring | Deferred Compensation Plan Investments [Member]
Schedule of Investments [Line Items]
Other investments	38	50
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Schedule of Investments [Line Items]
Other investments	25,592	34,165
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Iridium [Member]
Schedule of Investments [Line Items]
Other investments	25,592	34,165
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Deferred Compensation Plan Investments [Member]
Schedule of Investments [Line Items]
Other investments	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Schedule of Investments [Line Items]
Other investments	38	50
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Iridium [Member]
Schedule of Investments [Line Items]
Other investments	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Deferred Compensation Plan Investments [Member]
Schedule of Investments [Line Items]
Other investments	$ 38	$ 50