Summary Of Significant Accounting Policies (Accounting Changes To Consolidated Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended											12 Months Ended
	Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017		Dec. 31, 2016		Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Operating Activities
Net income	$ 7,459	[1]	$ 1,458	$ 19,052	$ 3,041		$ 354	[1]	$ 3,917	$ 2,922	$ 2,224	$ 31,010		$ 9,417	[2]	$ 23,031	[2]
Adjustments to reconcile net income to net cash flows from operating activities:
Change in net deferred tax assets												4,073		(5,060)		(4,067)
Other reconciling adjustments												191		19,128		5,786
Net changes in operating assets and liabilities:
Deferred revenue and other liabilities												(7,011)		3,626		(745)
Other operating assets and liabilities												(4,412)		3,077		4,569
Net cash provided by operating activities												23,851		30,188		28,574
Investing Activities
Net cash used in investing activities												(6,786)		(42,861)		(29,710)
Financing Activities
Net cash provided by / (used in) financing activities												(22,055)		11,246		(27,961)
Effect of exchange rate on cash												(359)		742		(1,449)
Net increase (decrease) in cash and cash equivalents												(5,349)		(685)		(30,546)
Cash and cash equivalents at the beginning of the year					19,017	[3]					19,702	19,017	[3]	19,702		50,248
Cash and cash equivalents at the end of the year	13,668						19,017	[3]				13,668		19,017	[3]	19,702
Without Breakage Revenue [Member]
Operating Activities
Net income												30,641		9,032
Adjustments to reconcile net income to net cash flows from operating activities:
Change in net deferred tax assets												3,834		(5,293)
Other reconciling adjustments												191		19,128
Net changes in operating assets and liabilities:
Deferred revenue and other liabilities												(6,403)		4,244
Other operating assets and liabilities												(4,412)		3,077
Net cash provided by operating activities												23,851		30,188
Investing Activities
Net cash used in investing activities												(6,786)		(42,861)
Financing Activities
Net cash provided by / (used in) financing activities												(22,055)		11,246
Effect of exchange rate on cash												(359)		742
Net increase (decrease) in cash and cash equivalents												(5,349)		(685)
Cash and cash equivalents at the beginning of the year					$ 19,017						19,702	19,017		19,702
Cash and cash equivalents at the end of the year	$ 13,668						$ 19,017					13,668		19,017		19,702
Previously Reported [Member]
Operating Activities
Net income																22,694
Adjustments to reconcile net income to net cash flows from operating activities:
Change in net deferred tax assets																(4,272)
Other reconciling adjustments																5,786
Net changes in operating assets and liabilities:
Deferred revenue and other liabilities																(203)
Other operating assets and liabilities																4,569
Net cash provided by operating activities																28,574
Investing Activities
Net cash used in investing activities																(29,710)
Financing Activities
Net cash provided by / (used in) financing activities																(27,961)
Effect of exchange rate on cash																(1,449)
Net increase (decrease) in cash and cash equivalents																(30,546)
Cash and cash equivalents at the beginning of the year											$ 19,702			19,702		50,248
Cash and cash equivalents at the end of the year																19,702
Adjustment [Member]
Operating Activities
Net income												369		385		337
Adjustments to reconcile net income to net cash flows from operating activities:
Change in net deferred tax assets												239		233		205
Net changes in operating assets and liabilities:
Deferred revenue and other liabilities												$ (608)		$ (618)		$ (542)

[1] Net income for the 4th quarter of 2017 includes approximately $2.5 million net tax benefit from non-recurring items of tax benefit and expense related to the Tax Cuts and Jobs Act enacted December 2017 and dissolution of a non-operating foreign subsidiary.

[2] Certain prior year balances have been reclassified to conform to the 2017 presentation (see Note 2 - Summary of Significant Accounting Policies - Reclassifications).

[3] Certain prior year balances have been reclassified to conform to the 2017 presentation (see Note 2 - Summary of Significant Accounting Policies - Reclassifications).