Commitments and Contingencies - Operating Leases (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 Integer	Dec. 31, 2012	Dec. 31, 2011
Operating Leases [Abstract]
Number of renewal options to extend the term of the lease	3
Commitments under operating leases [Abstract]
2014	$ 10,934,000
2015	9,853,000
2016	9,919,000
2017	9,429,000
2018	9,606,000
Thereafter	67,849,000
Total	117,590,000
Rent expense under operating leases [Abstract]
Rent expense under operating leases	9,875,000	8,029,000	7,790,000
Rent charges for utilities, real estate taxes, and operating expense	11,500,000	10,900,000	9,300,000
Tarrytown lease [Abstract]
Initial term of lease	15 years
Lease extension terms	5 years
Facilities
Commitments under operating leases [Abstract]
2014	8,765,000
2015	9,348,000
2016	9,895,000
2017	9,429,000
2018	9,606,000
Thereafter	67,849,000
Total	114,892,000
Rent expense under operating leases [Abstract]
Rent expense under operating leases	9,404,000	7,428,000	7,191,000
Equipment
Commitments under operating leases [Abstract]
2014	2,169,000
2015	505,000
2016	24,000
2017	0
2018	0
Thereafter	0
Total	2,698,000
Rent expense under operating leases [Abstract]
Rent expense under operating leases	$ 471,000	$ 601,000	$ 599,000
Tarrytown Lease
Operating Leases [Abstract]
Number of new buildings leased	2
Number of renewal options to extend the term of the lease	3
Lease renewal escalation percentage	2.50%
Number of new buildings to be constructed	2
Tarrytown lease [Abstract]
Lease extension terms	5 years