Supplemental Cash Flow Disclosures (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental cash flow disclosures
Interest paid	$ 54,955,000us-gaap_InterestPaid	$ 42,904,000us-gaap_InterestPaid	$ 44,048,000us-gaap_InterestPaid
Income taxes paid (refunded)	33,276,000us-gaap_IncomeTaxesPaidNet	157,778,000us-gaap_IncomeTaxesPaidNet	(58,609,000)us-gaap_IncomeTaxesPaidNet
Supplemental cash flows, stock based compensation
Cash receipts upon exercise of stock options	5,166,000	10,468,000	900,000
Cash disbursements for payments of taxes	(4,336,000)	(4,684,000)	(3,105,000)
Net cash receipts (disbursements) from exercise of stock options and vesting of other stock awards	830,000	5,784,000	(2,205,000)
Auction 901 Mobility Funds
Supplemental cash flow disclosures
FCC auction date	Sep. 27, 2012
Letters of credit outstanding	17,400,000
FCC auction amount received	13,400,000
FCC auction number of states won	10
Other assets and deferred charges \| Auction 901 Mobility Funds
Supplemental cash flow disclosures
FCC auction amount received	1,900,000
Property, plant and equipment, net \| Auction 901 Mobility Funds
Supplemental cash flow disclosures
FCC auction amount received	11,500,000
Maximum \| Auction 901 Mobility Funds
Supplemental cash flow disclosures
FCC auction amount	300,000,000
FCC auction amount awarded	40,100,000
Common Shares
Supplemental cash flows, stock based compensation
Shares withheld	163,355	606,582	92,846
Aggregate value of shares withheld	$ 6,868,000	$ 25,179,000	$ 3,604,000

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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The amount of cash paid for interest during the period.

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Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

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The total cash inflow associated with the amount received from holders to acquire the entity's shares under incentive and share awards, including stock option exercises. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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The total amount the Federal Communications Commission will award to successful auction bidders.

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The amount the entity was awarded in the Federal Communications Commission auction.

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The amount the entity received resulting from the Federal Communications Commission auction.

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Month, date and year in which the Federal Communications Commission auction took place.

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The number of states the entity won in the Federal Communications Commission auction.

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Amount of Letters of credit outstanding on revolving credit facility.

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For net-share settlement of share-based awards when the employer withholds shares for the exercise price and income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

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For net-share settlement of share-based awards when the employer withholds shares for the exercise price and income tax withholding obligations, this element represents the value of shares the employees use to repay the employer.

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