Summary of Significant Accounting Policies, Accounts Receivable (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts Receivable, Net [Abstract]
Unbilled contracts receivable	$ 260,400,000	$ 229,700,000
Allowance for Doubtful Accounts, Current [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance at beginning of the year	19,526,000	20,595,000	20,352,000
Charged to income	8,715,000	6,586,000	10,273,000
Write-off of uncollectible receivables	(8,552,000)	(7,858,000)	(10,901,000)
Reserves acquired from King Sturge	0	0	760,000
Impact of exchange rate movements and other	(906,000)	203,000	111,000
Allowance at end of the year	$ 18,783,000	$ 19,526,000	$ 20,595,000