Other Comprehensive Income (Other Comprehensive Income And Related Tax Effects) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other Comprehensive Income Loss [Line Items]
Amortization of prior service credits and net actuarial loss	$ 1,206	$ 209	$ 3,613	$ 595
Proportionate share of Telesat Holdco other comprehensive (loss) income, Net-of Tax Amount	444	(2,470)	465	(2,240)
Unrealized (loss) gain on foreign currency hedges	(128)	2,986	(298)	(6,307)
Less: reclassification adjustment for loss included in net income	681	4,054	3,764	7,750
Net unrealized gain (loss) on derivatives	553	7,040	3,466	1,443
Unrealized gain (loss) on available-for-sale securities	82	(485)	(48)	(614)
Other comprehensive income	2,285	4,294	7,496	(816)
Amortization of prior service credits and net actuarial loss, Tax (Expense) Benefit	(806)	(123)	(2,423)	(401)
Proportionate share of Telesat Holdco other comprehensive (loss) income, Tax (Expense) Benefit	(292)	1,790	(310)	1,508
Unrealized loss on foreign currency hedges, Tax (Effect) Benefit	85	(2,002)	200	4,246
Less: reclassification adjustment for loss included in net income, Tax (Expense) Benefit	(453)	(2,731)	(2,526)	(5,216)
Net unrealized gain (loss) on derivatives, Tax (Expense) Benefit	(368)	(4,733)	(2,326)	(970)
Unrealized gain (loss) on available-for-sale securities, Tax (Expense) Benefit	(56)	323	31	410
Other comprehensive income (loss), Tax (Expense) Benefit	(1,522)	(2,743)	(5,028)	547
Amortization of prior service credits and net actuarial loss	2,012	332	6,036	996
Proportionate share of Telesat Holdco other comprehensive (loss)income, Before-Tax Amount	736	(4,260)	775	(3,748)
Unrealized (loss) gain on foreign currency hedges	(213)	4,988	(498)	(10,553)
Less: reclassification adjustment for loss included in net income	1,134	6,785	6,290	12,966
Net unrealized gain (loss) on derivatives	921	11,773	5,792	2,413
Unrealized gain (loss) on available-for-sale securities	138	(808)	(79)	(1,024)
Other comprehensive income	$ 3,807	$ 7,037	$ 12,524	$ (1,363)