using System;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var regex = new Regex(@"(?<=Paybacks[:\s]*)[^\s:].*", RegexOptions.IgnoreCase);
        string[] strings = {"Paybacks: blah", "Paybacks blah", "Paybacks                  blah"};
        
        foreach (String s in strings)
        {
            Console.WriteLine(regex.Match(s)?.Value);
        }
	}
}