Acquisitions (Pro Forma Results of Operations) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Business Acquisition [Line Items]
Total revenues	$ 260,029	$ 207,984	$ 505,101	$ 405,722
Net income (loss) attributable to controlling interests and available to common stockholders	13,989	15,327	23,554	24,757
Net income per common share - basic	$ 0.31	$ 0.34	$ 0.53	$ 0.54
Net income per common share - diluted	$ 0.31	$ 0.33	$ 0.52	$ 0.54
Cardpoint Limited [Member]
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue		233,920		457,594
Business Acquisition, Pro Forma Net Income		$ 16,094		$ 25,374
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 0.35		$ 0.56
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0.35		$ 0.55