CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock for common stock (in shares)		149,886	1,897
Issuance of shares in connection with acquisitions (in shares)	35,714	498,730
Issuance of shares upon conversion of notes to common stock (in shares)		493,791
Acquisition of shares of common stock (in shares)	65,171
Vesting of restricted stock for shares of common stock	68,069