Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 4,636	$ 2,010
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	909	686
Amortization and change in contingent consideration	4,462	4,438
Stock-based compensation	1,073	559
Revaluation of warrants		26
Loss on disposal of fixed assets	71	24
Provision for doubtful accounts	35	70
Deferred taxes	2,407	1,006
Excess tax benefit from the exercise of stock options	(2,511)
Changes in operating assets and liabilities:
Accounts receivable	(9,819)	(3,244)
Prepaid expenses and other current assets	(2,600)	172
Other assets	104	(6)
Accounts payable and accrued expenses	(3,941)	(1,911)
Customer obligations	9,952	3,113
Other liabilities	530	1,056
Net cash provided by operating activities	5,308	7,999
Cash flows used in investing activities:
Purchases of property and equipment	(3,611)	(2,992)
Cash consideration for business acquisitions, net of cash acquired		8,551
Cash paid for acquisition of client contracts	(945)
Change in restricted cash	3,249	112
Net cash provided by (used in) investing activities	(1,307)	5,671
Cash flows from financing activities:
Proceeds from debt		29,630
Proceeds from follow-on offering net of underwriters commissions and discounts	11,550
Proceeds from exercise of common stock options	5,588	1
Proceeds from issuance of common stock (Employee Stock Purchase Plan)	480
Purchase of treasury stock		(4)
Excess tax benefit from the exercise of stock options	2,511
Net cash provided by financing activities	20,129	29,627
Net increase in cash and cash equivalents	24,130	43,297
Cash and cash equivalents at beginning of period	305,052	154,621
Cash and cash equivalents at end of period	329,182	197,918
Cash paid during the period for:
Interest	873	151
Taxes	54	357
Noncash financing and investing activities:
Accretion of redemption premium		1,523
Reduction in FBM contingent consideration due to re-negotiated lease		$ 528