Server error gets displayed on click of Subrate which is added with Coverage Amount in multiple numbers.

Replication Steps:
1. Login as Partner
2. Go to Test Company > Rates
3. Select 'Life' rate
4. Add new Sub rate with coverage amount value like 7500000000000000000000000 or 1254820004 any value with maximum amount.
5. Click on newly added sub rate.

Upper limit for coverage amount is not validated.

Error Log :
Exception : Conversion overflows.
App Error Log : ControllerAppTier.GetData->BenAdminControllerAppTier.GetData->Rate.GetData->Rate.GetRateForGivenID
Employee ID : 0
Action Name : SubRates
Model : System.Web.Mvc.HandleErrorInfo
Controller : Customization
Web Error Log : at WORKTERRA.BenAdmin.BenAdminControllerWebTier.GetData(ObjectType I_objectType, Hashtable I_criteria, Object I_context, Boolean I_mode, Boolean I_needCollection)
at WORKTERRA.BenAdmin.Areas.Customization.Models.RateSubRatesModel.RateSubRatesDetails(String Parameter1, Int32 SubRateID, String SubRateName)
at WORKTERRA.BenAdmin.Areas.Customization.Controllers.CustomizationController.SubRates(String Parameter1, Int32 SubRateID, String SubRateName)
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.<>c_DisplayClass15.b_12()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.<>c_DisplayClass15.<>cDisplayClass17.b_14()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.<>c_DisplayClass15.<>cDisplayClass17.b_14()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)

CC : Rakesh RoyHrishikesh DeshpandeSachin HingoleSatyaAmruta LohiyaSamirGaurav Sodani