Condensed Consolidating Financial Information - Condensed Consolidating Statement of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash used in operating activities	$ (36,583)	$ (52,596)
Cash flows from investing activities
Purchase of office facilities	(474)	(1,397)
Cash used in investing activities	(474)	(1,397)
Cash flows from investing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	(1,511)	(1,486)
Issuance of Class A non-voting common stock	0	185
Tax benefit (deficiency) from share-based awards	(321)	1,242
Other financing activities	42,000	78,800
Cash flow provided by (used in) financing activities	40,168	78,741
Net increase (decrease) in cash and cash equivalents	3,111	24,748
Cash and cash equivalents, beginning of period	63,807	98,294
Cash and cash equivalents, end of period	66,918	123,042
Parent Company [Member]
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash used in operating activities	1,394	209
Cash flows from investing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	(1,511)	(1,486)
Issuance of Class A non-voting common stock		185
Tax benefit (deficiency) from share-based awards	(321)	1,242
Cash flow provided by (used in) financing activities	(1,832)	(59)
Net increase (decrease) in cash and cash equivalents	(438)	150
Cash and cash equivalents, beginning of period	439	448
Cash and cash equivalents, end of period	1	598
Guarantor Subsidiaries [Member]
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash used in operating activities	436	27,296
Cash flows from investing activities
Net increase (decrease) in cash and cash equivalents	436	27,296
Cash and cash equivalents, beginning of period	1,557	30,901
Cash and cash equivalents, end of period	1,993	58,197
Non-Guarantor Subsidiaries [Member]
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash used in operating activities	(38,413)	(80,101)
Cash flows from investing activities
Purchase of office facilities	(474)	(1,397)
Cash used in investing activities	(474)	(1,397)
Cash flows from investing activities
Other financing activities	42,000	78,800
Cash flow provided by (used in) financing activities	42,000	78,800
Net increase (decrease) in cash and cash equivalents	3,113	(2,698)
Cash and cash equivalents, beginning of period	61,811	66,945
Cash and cash equivalents, end of period	$ 64,924	$ 64,247