Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 01, 2016
Income Tax Contingency [Line Items]
Deferred tax liabilities	$ 27,480	$ 24,229
Valuation allowance recorded during the period	2,055	589	$ 2,273
Deferred tax assets expected to be realized	395,400
Valuation allowance	9,658	11,713
Deferred tax assets, not subject to expiration	213,900
Unrecognized tax benefits, income tax penalties and interest accrued	38	96	109
Unrecognized tax benefits that would impact effective tax rate	9,900	8,300	$ 8,500
Unrecognized tax benefits, income tax penalties and interest accrued that would impact effective tax rate	25	$ 63
Approximate range of uncertain income tax positions expected to be settled or resolved during the next 12 months, minimum	80
Period through 2019 [Member]
Income Tax Contingency [Line Items]
Valuation allowance	9,700
Period from 2030 through 2032 [Member]
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	126,400
Period through 2035 [Member]
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	40,700
Federal [Member]
Income Tax Contingency [Line Items]
Alternative minimum tax credits	43,000
Federal and State [Member] | Period through 2035 [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward, amount	$ 24,000
Global One [Member]
Income Tax Contingency [Line Items]
Deferred tax liabilities				$ 3,100