Financing Agreements - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended							1 Months Ended						1 Months Ended						1 Months Ended							1 Months Ended								1 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Aug. 31, 2009 Amended and Restated Credit Agreement	Mar. 22, 2012 Second Amended Restated Credit Agreement	Mar. 22, 2012 Second Amended And Restated Credit Agreement Minimum	Mar. 22, 2012 Second Amended And Restated Credit Agreement Maximum	Jun. 30, 2013 London Interbank Offered Rate (LIBOR)	Mar. 22, 2012 London Interbank Offered Rate (LIBOR) Second Amended Restated Credit Agreement	Mar. 22, 2012 London Interbank Offered Rate (LIBOR) Second Amended Restated Credit Agreement Scenario 1 Minimum	Mar. 22, 2012 London Interbank Offered Rate (LIBOR) Second Amended Restated Credit Agreement Scenario 1 Maximum	Mar. 22, 2012 London Interbank Offered Rate (LIBOR) Second Amended Restated Credit Agreement Scenario 2 Minimum	Mar. 22, 2012 London Interbank Offered Rate (LIBOR) Second Amended Restated Credit Agreement Scenario 2 Maximum	Jun. 30, 2013 Federal Funds Rate	Mar. 22, 2012 Federal Funds Rate Second Amended Restated Credit Agreement	Jun. 30, 2013 Prime Lending Rate	Jun. 30, 2013 Senior Unsecured Revolving Credit Facility	Dec. 31, 2007 Senior Unsecured Revolving Credit Facility	Jun. 30, 2013 Senior Unsecured Revolving Credit Facility Amended and Restated Credit Agreement	Aug. 31, 2009 Senior Unsecured Revolving Credit Facility Amended and Restated Credit Agreement	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Second Amended Restated Credit Agreement	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Second Amended Restated Credit Agreement Minimum	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Second Amended Restated Credit Agreement Maximum	Dec. 31, 2012 Senior Unsecured Revolving Credit Facility China HR Credit Facility	Dec. 31, 2011 Senior Unsecured Revolving Credit Facility China HR Credit Facility	Dec. 31, 2007 Senior Unsecured Revolving Credit Facility Letter of Credit	Jun. 30, 2013 Senior Unsecured Revolving Credit Facility Letter of Credit Amended and Restated Credit Agreement	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Letter of Credit Second Amended Restated Credit Agreement Minimum	Mar. 22, 2012 Senior Unsecured Revolving Credit Facility Letter of Credit Second Amended Restated Credit Agreement Maximum	Jun. 30, 2013 Term Loan Facility Third Quarter	Jun. 30, 2013 Term Loan Facility Fourth Quarter	Jun. 30, 2013 Term Loan Facility First Quarter	Jun. 30, 2013 Term Loan Facility Second Quarter	Jun. 30, 2013 Term Loan Facility Amended and Restated Credit Agreement	Aug. 31, 2009 Term Loan Facility Amended and Restated Credit Agreement	Mar. 22, 2012 Term Loan Facility Second Amended Restated Credit Agreement	Jun. 30, 2013 Credit Facility Term Loans Amended and Restated Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowings under senior unsecured revolving credit facility			$ 300,000	$ 325,000													$ 250,000		$ 250,000	$ 225,000			$ 5,049	$ 7,574	$ 50,000									$ 50,000	$ 100,000
Payments on borrowings on credit facilities	39,799	271,516																		172,500
Payments on borrowings on term note	3,125	41,250																																	40,000
Debt instrument maturity date																				Mar. 22, 2015															Mar. 22, 2015
Amortization payments on outstanding principal amount of term loans, in next twelve months																													1,875	1,875
Amortization payments on outstanding principal amount of term loans, in year two																													2,500	2,500	1,875	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																		45,700								994							93,125
Utilized portion of credit facility , due with in one year																																				8,125
Credit facility, available to be utilized																$ 178,306
Interest rate at the end of period							0.19%						0.07%		3.25%
Interest rate at the end of period, effective							2.94%