Financing Agreements - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended																			1 Months Ended		1 Months Ended		3 Months Ended				1 Months Ended							1 Months Ended			3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Aug. 31, 2009 First Amended And Restated Credit Agreement	Mar. 22, 2012 Second Amended And Restated Credit Agreement	Mar. 22, 2012 Second Amended And Restated Credit Agreement Minimum	Mar. 22, 2012 Second Amended And Restated Credit Agreement Maximum	Sep. 30, 2012 British Bankers Association Libor	Mar. 22, 2012 British Bankers Association Libor Second Amended And Restated Credit Agreement	Mar. 22, 2012 British Bankers Association Libor Second Amended And Restated Credit Agreement Scenario 1 Minimum	Mar. 22, 2012 British Bankers Association Libor Second Amended And Restated Credit Agreement Scenario 1 Maximum	Mar. 22, 2012 British Bankers Association Libor Second Amended And Restated Credit Agreement Scenario 2 Minimum	Mar. 22, 2012 British Bankers Association Libor Second Amended And Restated Credit Agreement Scenario 2 Maximum	Sep. 30, 2012 Federal Funds Rate	Mar. 22, 2012 Federal Funds Rate Second Amended And Restated Credit Agreement	Sep. 30, 2012 Prime Lending Rate	Sep. 30, 2012 One Month LIBOR	Sep. 30, 2012 Senior Unsecured Revolving Credit Facility	Dec. 31, 2007 Senior Unsecured Revolving Credit Facility	Aug. 31, 2009 Senior Unsecured Revolving Credit Facility First Amended And Restated Credit Agreement	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Second Amended And Restated Credit Agreement	Sep. 30, 2012 Senior Unsecured Revolving Credit Facility Second Amended And Restated Credit Agreement	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Second Amended And Restated Credit Agreement Minimum	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Second Amended And Restated Credit Agreement Maximum	Jun. 30, 2011 Senior Unsecured Revolving Credit Facility China HR Credit Facility	Sep. 30, 2012 Senior Unsecured Revolving Credit Facility China HR Credit Facility	Dec. 31, 2007 Senior Unsecured Revolving Credit Facility Letter of Credit	Sep. 30, 2012 Senior Unsecured Revolving Credit Facility Letter of Credit Second Amended And Restated Credit Agreement	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Letter of Credit Second Amended And Restated Credit Agreement Minimum	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Letter of Credit Second Amended And Restated Credit Agreement Maximum	Sep. 30, 2012 Term Loan Facility Second Quarter	Sep. 30, 2012 Term Loan Facility Third Quarter	Sep. 30, 2012 Term Loan Facility Fourth Quarter	Sep. 30, 2012 Term Loan Facility First Quarter	Aug. 31, 2009 Term Loan Facility First Amended And Restated Credit Agreement	Mar. 22, 2012 Term Loan Facility Second Amended And Restated Credit Agreement	Sep. 30, 2012 Term Loan Facility Second Amended And Restated Credit Agreement	Sep. 30, 2012 Credit Facility Term Loans Second Amended And Restated Credit Agreement	Jun. 30, 2012 Senior Secured Revolving Credit Facility China HR Credit Facility	Sep. 30, 2012 Senior Secured Revolving Credit Facility China HR Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowings under senior unsecured revolving credit facility			$ 300,000	$ 325,000														$ 250,000	$ 250,000	$ 225,000				$ 7,494		$ 50,000								$ 50,000	$ 100,000			$ 4,996
Payments on borrowings on credit facilities	271,802	9,500																		172,500
Payments on borrowings on term note	42,500																																		40,000
Debt instrument maturity date																				Mar. 22, 2015				Mar. 01, 2013											Mar. 22, 2015
Amortization payments on outstanding principal amount of term loans, in year two																														1,875		1,250	1,250
Amortization payments on outstanding principal amount of term loans, in year three																														2,500	1,875	1,875	1,875
Amortization payments on outstanding principal amount of term loans, in year three																															2,500	2,500
Debt instrument, basis spread on variable rate								1.00%	2.50%	3.25%	1.50%	2.25%		0.50%
Fee on all outstanding amounts of letters of credit																												2.50%	3.25%
Commitment fee on the unused portion of the revolving credit facility																						0.35%	0.50%
Consolidated Leverage Ratio						3.00
Interest charge coverage ratio					3.00
Utilized portion of credit facility																					90,500				5,641		6,376									97,500			2,300
Utilized portion of credit facility , due with in one year																																					6,250
Credit facility, available to be utilized																	$ 128,124								$ 1,853														$ 2,696
Interest rate at the end of period							0.21%						0.09%		3.25%
Interest rate at the end of period, effective																2.72%
Tenure of credit facility																								1 year														1 year
Interest rate at the end of period																									6.25%														6.02%