CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 504	$ 4,037
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	7,680	7,195
Amortization of intangible assets	3,172	1,294
Amortization of debt discount and issuance costs	516
Provision for doubtful accounts	445	486
Stock-based compensation and charges	8,241	5,856
Earnings of unconsolidated joint venture	(1,650)	(710)
Return on investment in unconsolidated joint venture	602	255
Other noncash items	(5)	(40)
Changes in operating assets and liabilities:
Accounts receivable	(1,180)	(1,100)
Other assets	(932)	(144)
Accounts payable and accrued expenses	4,114	2,816
Deferred revenue	(722)	(1,163)
Net cash provided by operating activities	20,785	18,782
Cash flows from investing activities:
Purchases of property and equipment	(8,957)	(6,672)
Proceeds from sale of assets		9
Acquisitions, net of cash acquired	(2,250)	(22,000)
Return of investment in unconsolidated joint venture	582	724
Net cash used in investing activities	(10,625)	(27,939)
Cash flows from financing activities:
Principal payments on loan payable	(19)	(82)
Proceeds from issuance of convertible senior notes, net of issuance costs	96,608
Redemption of convertible preferred stock		(49,044)
Payment of dividend on convertible preferred stock		(882)
Proceeds from exercise of stock options	8,216	3,060
Tax payments related to net share settlements of equity awards	(2,405)	(529)
Repurchase of common stock	(26,010)	(69)
Net cash provided by (used in) financing activities	76,390	(47,546)
Change in cash and cash equivalents	86,550	(56,703)
Cash and cash equivalents, beginning of period	27,122	87,579
Cash and cash equivalents, end of period	$ 113,672	$ 30,876